Due to the uncertainty of the investment environment, stakeholders are considering sustainability, and their perception of ESG is changing. The National Pension Service, a public pension fund and institutional investor, is expanding from bond-based investments to equity investments in order to find ways to delay the depletion of funds. Fulfilling the role of institutional investors through institutional changes such as the “Plan to Promote Responsible Investment of the National Pension Fund” will inevitably have a direct or indirect impact on the overall economy, and to this end, this study aims to find ways for companies to respond by presenting the results of analysis by group and diagnosing the impact of changes in investment strategies by comparing and analyzing the before-and-after effects. As a result of the study, the mediating effect of the investment equity ratio of the National Pension Plan on the relationship between ESG and corporate value was greater after the institutional change than before the institutional change, and the need for ESG increased by companies. In addition, in order to ensure the robustness of the analysis, it was categorized into manufacturing and non-manufacturing sectors, suggesting measures to respond to each industry to which the company belongs.