This study was conducted with the purpose of contributing to differentiate the non-financial ESG rating from the existing financial credit rating, and suggesting a direction for the ESG rating evaluation method in the future. ESG ratings and financial factors are significantly related as found in previous studies. A causality can be debated, as a cycle may arise in which past ESG ratings influence the current financial factors, and past financial factors in turn influence the current ESG ratings. However, given the high influence of financial credit ratings and the relatively low influence of ESG ratings as perceived by market participants at the present time, it is possible to support the reverse assumption rather than the assumption that ESG ratings have a lasting effect on financial factors. In this study, assuming that the cause is the company's financial factor and the result is the ESG ratings, we attempted to find a meaningful relationship by collecting and doing regression analysis of data for multiple years. In order to support the results, analysis using recent cross-sectional data, analysis using balanced panel data, and case study of exceptional companies significantly deviating from the regression line were performed additionally. As a result, it was found that the financial factors of a company have a significant effect on the ESG rating of the following year. In particular, it is observed that large size companies tend to receive higher ESG ratings. In addition, it is observed that the higher the proportion of intangible assets, the lower the share of the largest shareholder, and the higher foreign ownership, the better the ESG rating. In evaluating and granting ESG ratings, the impact of corporate size should be considered so that small businesses can also pay attention to ESG activities: i) by developing new ESG evaluation indicators for small businesses, ii) by dividing groups and calculating ESG ratings based on the size of firms.