This study aims to determine the simultaneous and partial effect of the total asset turnover ratio, return on asset, and dividend policy on the Investment Opportunity Set (IOS). Investment Opportunity Set (IOS) is a concept used to assess a company in the form of a combination of assets and investment options in the future. The population in this study are companies listed in the LQ45 index on the Indonesia Stock Exchange for the 2017-2020 period. The method used in this research is the quantitative method and the sample selection method uses the purposive sampling technique. This study has 104 observational data obtained from 26 samples of companies. The data analysis used in this research is panel data regression analysis using Eviews 12. The result shows that the total asset turnover ratio, return on assets, and dividend policy have a simultaneous effect on the Investment Opportunity Set (IOS). Partially, the total asset turnover ratio has no effect on the Investment Opportunity Set (IOS), return on asset and dividend policy have a positive effect on the Investment Opportunity Set (IOS).