ESGスコア：定義、使用例、重要性、改善方法 

ESG ratings and scores have become essential tools for measuring how companies manage environmental, social, and governance risks, and the stakes have never been higher. A 2025 PwC survey found that 78% of investors report that sustainability metrics directly improve their interest and confidence in a company. Whether you’re an investor evaluating long-term risk, a procurement professional managing your supply chain or a business looking to attract capital, understanding ESG ratings is essential. Here, we break down what ESG ratings are, how they’re calculated and how companies can work to improve them.

Key Takeaways  ESG ratings provide a structured overview of an organization’s environmental, social and governance risks. While an ESG score is often a raw numerical value, a rating offers a relative assessment against industry peers. Investors use these metrics to evaluate long-term risk, and 78% say sustainability metrics directly improve their confidence in a company. ESG ratings are increasingly tied to real financial outcomes, influencing access to capital, borrowing rates and supply chain partnerships. Improving your ESG rating requires a clear roadmap across all three pillars, from reducing environmental impact to strengthening governance structures.

What is an ESG Rating?

ESG stands for Environmental, Social and Governance — a framework used to evaluate how a company manages risks and opportunities across three interconnected areas. Originally developed as a tool for socially responsible investing, ESG has evolved into a broad lens for assessing corporate sustainability and accountability.

1. 環境 (E)：カーボンフットプリント、資源利用、廃棄物管理などの自然環境に対する影響。
2. 社会 (S)：多様性、労働慣行、地域社会とのかかわりを中心とした従業員、クライアント、地域社会との関係性。
3. ガバナンス (G)：リーダーシップ、企業倫理、企業における意思決定の透明性。

An ESG rating is an independent assessment of an organization’s performance across these three pillars, typically produced by a specialized rating agency such as MSCI, Sustainalytics or S&P Global based on publicly available data disclosures.

ESG Ratings and ESG Scores: What’s the Difference?

​​While the terms are often used interchangeably, ESG ratings and ESG scores refer to slightly different outputs. An ESG score is a numerical result, typically expressed on a scale of 0 to 100, that quantifies a company’s ESG performance. An ESG rating is a categorical classification, such as a letter grade (AAA to CCC) or a risk tier (low, medium or high), that assigns performance to a defined category.

Some agencies, like MSCI, use letter-grade ratings. Others, like Sustainalytics, use numerical risk scores. EcoVadis Ratings uses a 0 to 100 scoring model paired with medal tiers (Bronze, Silver, Gold and Platinum) to help companies and their partners benchmark performance at a glance. In practice, both terms are widely used to describe the overall output of an ESG assessment.

How Are ESG Scorecards and Ratings Used?

ESG ratings serve a wide range of stakeholders, from institutional investors to corporate procurement teams and financial institutions. Below are the primary ways organizations are putting ESG ratings to work.

Investment Decisions 

Investors increasingly prioritize companies with strong ESG performance, as they are seen as more sustainable and less risky in the long term. For publicly traded companies, ratings providers play a distinct role in how that risk is understood and acted upon. Morningstar/Sustainalytics offers detailed ESG risk ratings to help investors understand how environmental and social risks could impact a company’s valuation. Their scoring system identifies material ESG issues relevant to specific industries. Moody’s ESG Solutions (Vigeo Eiris) provides ESG assessments integrated with credit risk analysis, helping fixed-income investors assess long-term risks. Institutional investors rely on these scores to build ESG-focused portfolios or screen out high-risk companies.

In private equity, ESG ratings serve a related but distinct purpose. Investors assess ESG scores to identify potential risks and opportunities in their portfolio companies. Firms with strong ESG performance are often seen as lower risk and better positioned for long-term success. Private equity firms use ESG scores to monitor and improve the sustainability practices across their portfolio, enhancing value creation.

Sustainable Procurement & Supply Chain Management 

1. 規制コンプライアンス：多くの国で、企業にESGメトリクスの報告義務が法制度として導入されようとしています。
2. Brand Reputation: Companies with high ESG scores often enjoy better reputations, thereby attracting customers, employees, and partners.
3. サプライチェーンのリスクマネジメント：ESGを重視する企業は、気候変動、労働者によるストライキ、不祥事といった環境や社会、ガバナンスリスクへの対処に向けた準備を怠らない傾向があります。
4. Financial Performance: Research indicates that companies with high ESG scores often outperform their peers financially over time.

How Are ESG Scores & Ratings Calculated?

それぞれの格付け機関は独自のサステナビリティ/ESG評価手法を有していますが、一般的には以下のようなものが含まれます。

1. Data Collection

Before scoring can take place, rating agencies gather information from a range of sources to build a comprehensive picture of a company’s ESG performance.

1. 企業が提供するデータ：企業は、方針、プログラム文書、報告書、記録といった詳細情報を提出します。これは、サステナビリティまたはCSRレポート、環境影響評価、ガバナンス体制といったものです。
2. 外部情報源：アナリストは、報道機関、規制機関、非政府組織（NGO）などの信頼のおける情報源から得たデータを検証します。これには、米国に拠点を置く非営利団体China Labor Watchや米国環境保護庁(EPA)などの組織が発行する監視報告書が含まれます。
3. 認証および基準：ISO14001（環境マネジメント）、ISO26000（社会的責任）、森林管理協議会（FSC）ラベルなどの認証を有していることは、ESGスコアに有利に働きます。これらの認証は、高く評価されたサステナビリティ基準を遵守していることを示すものです。
4. 監査報告書：第三者による監査結果には、企業のESG基準への準拠に関する知見が記載されています。このような監査は、実施された方針の有効性を評価し、改善すべき領域を特定するものです。

 

2. Assessment:

Once data is collected, analysts evaluate the company’s policies, practices and performance against ESG criteria. This is not a purely mechanical process, as assessors must consider the relevance of specific issues to a company’s industry and geography, recognizing that material ESG risks vary across sectors. A mining company, for example, faces very different environmental exposures than a software firm.

3. Weighting and Scoring:

ESG factors carry different weights depending on the company or industry being assessed. A carbon-intensive manufacturer will be evaluated more heavily on environmental metrics, while a financial services firm may be weighted more toward governance and social factors. This industry-specific weighting is designed to ensure that scores reflect material risk rather than a one-size-fits-all checklist.

5. Final Rating:

The weighted scores across all ESG factors are combined to produce an overall ESG score or rating, often expressed on a numerical scale or as letter grades.

高水準のESGレーティングメトリクスでは、定量的データ（例：排出量メトリクスや多様性統計）と定性的評価（例：方針の有効性やガバナンスの質）の両方を統合したものとなります。また、業種特有の要因や地域の規制環境が考慮される場合もあります。グローバル・レポーティング・イニシアチブ（GRI）は、企業がサステナビリティ関連情報を開示する際の指針となる基準であり、世界的な期待や規制の枠組みとの整合性が確保されています。

Challenges in ESG Rating 

Despite their growing adoption, ESG ratings are not without criticism. Understanding their limitations is important for anyone relying on them to make informed decisions.

• Data Gaps: Limited or inconsistent data availability can make accurate scoring difficult. Companies without robust reporting infrastructure or operating in regions with limited regulatory oversight are particularly vulnerable to incomplete assessments.
• Subjectivity: ESG rating agencies may have varying standards, and the weight assigned to individual factors can differ significantly between providers, making direct comparisons across companies or sectors unreliable.
• ​​Scope Limitations: ESG ratings tend to focus on how organizations manage internal processes rather than the real-world impact of their products and services. An organization might score well on governance and operational efficiency while still producing products with significant environmental or social consequences.
• Greenwashing: Companies might exaggerate their ESG efforts to appear more sustainable than they are., undermining the credibility of ratings and making it harder for stakeholders to distinguish genuine progress from performative reporting.

Conflicts of Interest: Some ESG rating providers face commercial pressures that can influence scoring outcomes, raising questions about objectivity and consistency.

How to Improve ESG Scores & Ratings

For many companies, an initial ESG assessment reveals gaps that require more than just awareness of the score itself. Meaningful improvement depends on having a clear roadmap that addresses performance across all three pillars and builds the internal capacity to progress over time.

環境 (E) 

Reducing environmental impact is often the most visible dimension of ESG performance, encompassing operational decisions and how transparently they are reported.

• Reduce Carbon Footprint: Invest in renewable energy, energy-efficient technologies, and carbon reduction programs.
• Sustainable Practices: Optimize resource use, implement recycling programs, and reduce waste.
• Environmental Reporting: Publish clear and transparent data on environmental initiatives and outcomes.

社会 (S)

Social performance reflects how an organization treats the people it works with and the communities it operates in. Investors and procurement partners increasingly scrutinize this dimension as a signal of long-term stability and cultural health.

• Diversity and Inclusion: Establish policies to ensure workforce diversity and equal opportunities.
• Employee Well-being: Promote fair wages, safe working conditions, and mental health support.
• Community Engagement: Support local communities through charitable initiatives, volunteer programs, and partnerships.

ガバナンス (G)

Governance is the foundation that makes the other two pillars credible. Without transparent leadership and accountability structures, even strong environmental and social performance can be called into question.

• Transparency: Maintain open and transparent communication with stakeholders, including robust financial and ESG reporting.
• Ethics and Anti-Corruption Practices: Enforce ethical guidelines and avoid conflicts of interest at all levels, including the board and executives.
• Accountability: Create mechanisms for stakeholder feedback and establish oversight committees.

ESG Ratings as a Driver of Sustainable Growth  

Environmental, Social, and Governance (ESG) scores are no longer just a metric for corporate responsibility,—they have evolved into a critical factor for driving sustainable growth. Companies that prioritize ESG principles create long-term value for stakeholders, mitigate risks, and adapt to shifting global challenges.

1. Attracting Long-term Investment: ESG-aligned investments are growing, with asset managers prioritizing companies that demonstrate strong ESG performance. Organizations with higher ESG ratings may also secure financing more affordably, as they are perceived as lower-risk by lenders, reducing their overall cost of capital.
2. Enhancing Operational Efficiency: Reducing resource consumption and transitioning to renewable energy can lower operational costs, while implementing sustainable practices such as circular economy principles minimizes waste and enhances productivity. Proactively addressing ESG risks like regulatory changes, climate risks and social unrest, also strengthens long-term resilience.
3. Strengthening Brand and Market Position: Consumers increasingly prefer brands that align with their values, particularly in sustainability and ethics, giving ESG leaders a competitive advantage. High ESG ratings also help mitigate reputational risks, reducing the impact of potential scandals or negative publicity.
4. Fostering Innovation and Growth: ESG priorities drive the development of sustainable products and services, opening new markets and revenue streams. Companies often leverage advanced technologies such as AI, IoT and blockchain to meet ESG goals, boosting overall efficiency, while an inclusive and purpose-driven culture inspires employees to contribute ideas and drive business growth.
5. Building Stakeholder Trust: ESG-focused companies strengthen relationships with local communities, earning goodwill and social license to operate. Fair labor practices, diversity initiatives and a focus on employee well-being improve recruitment and retention, while transparent ESG reporting and strong governance reassure shareholders about long-term profitability and sustainability.
6. Aligning with Global Goals and Regulations: Governments worldwide are enforcing stricter ESG regulations, such as mandatory carbon disclosures and gender diversity quotas, and high ratings help ensure compliance and reduce legal risks. Companies aligned with the United Nations Sustainable Development Goals (SDGs) also demonstrate commitment to addressing global challenges like climate action, poverty reduction and gender equality.

最後に

ESG scores represent a paradigm shift in how businesses approach growth. By prioritizing long-term sustainability over short-term profits, companies can unlock new opportunities, mitigate risks, and create value for all stakeholders. But a strong ESG rating doesn’t happen by accident. It requires embedding ESG goals into core business strategy, committing to transparent and consistent reporting, and investing in the partnerships and technologies that drive meaningful progress.

For organizations looking to understand where they stand and where to focus, EcoVadis provides the ratings, scorecards and actionable insights needed to turn ESG ambition into measurable results.