The background of this study was the difference of previous studies results regarding the relations between size, capital intensity ratio, leverage, and profitability of a company towards effective tax rate (ETR). Therefore, the problem to be solved is how size, capital intensity ratio, leverage, and profitability affect effective tax rate. This study aimed to examine the impact of size, capital intensity ratio, leverage, and profitability of a company on effective tax rate. This study was performed on companies listed in the Indonesia Stock Exchange (IDX) in 2013-2016 period. The number of observations is 124 samples which are obtained by non probability sampling method which is purposive sampling technique. The analysis technique applied in this research is multiple linear regression analysis. The analysis showed that leverage positively affects effective tax rate. It means that higher leverage will result in higher effective tax rate. Profitability negatively affects effective tax rate. It indicates that higher profitablity will result in lower effective tax rate. Meanwhile size and capital intensity ratio have no impact on effective tax rate. Overall, the independent variables in this research can determine 61.1% of effective tax rate. This implies that there is still 38.9% of factors which can be explained by other variables, hence it is expected that future research could find the unknown variables.