The aim of this research is to test some variables, such as systematic risk, asset tangibility, profitability, and firm’s type which have the impact on capital structure based on static trade-off hypothesis and find the evidence that shows firm’s type measured by dummy variable acting as the moderating variable. The sample that we use is taken from the companies of mining industry in Indonesian Stock Exchange. Purposive sampling technique is used as the sampling method. The analysis of covariance (ANCOVA) model with polled data is conducted as the method of data analysis. To test the firm’s type which acts as moderating variable, we use the significance of R-square change before and after the interaction effects are involved in the regression model. The result reveals that systematic risk, profitability, and firm’s type support static-trade off hypothesis for explaining the capital structure. In addition, increase in R-square significantly gives the evidence that firm’s type acts as the moderating variable.