AbstrakThe purpose of this study was to analyze the effect of firm size using Debt to Equity Ratio, Return on Assets, and Earning per Share on the level of initial stock underpricing on the Indonesia Stock Exchange.The population in this study were companies that carried out IPOs in 2012 - 2013. Samples were selected using purposive sampling technique, and the sample are 13 companies. Data collection is done by taking company financial report data from the Indonesian Capital Market Directory (ICMD) book and downloading the official website of the Indonesia Stock Exchange. The analytical method used is multiple linear regression analysis with SPSS version 23.0.The results showed that the Company Size had a negative and insignificant effect on the initial stock undepricing level on the Indonesia Stock Exchange. Debt to Equity Ratio has a negative and significant effect on the level of initial stock underpricing on the Indonesia Stock Exchange. Return on Assets has a negative and significant effect on the level of initial stock underpricing on the Indonesia Stock Exchange. Earning per Share has a positive and insignificant effect on the level of initial stock underpricing on the Indonesia Stock Exchange. Keywords: Company Size, Debt to Equity Ratio, Return on Assets, Earning per Share and Underpricing.