This study has examined the effects of the Each revision periods of the underwriting rules in 2002(a partial revision period) and 2007(a full revision period). For this study, 615 samples were chosen from firms listed in Korea(2000∼2008). this study we throughly reviewed the impact of the full revision of underwriting of IPOs based on two aspects : First, we empirically tested whether degree of the initial issue price can be adjusted or not after the revision of each periods(Hypothesis 1); Second, Whether the initial abnormal of return of IPO after market can be reduced each periods or not(Hypothesis 2) The major results from the study are as follows: First, the full revision of the underwriting rules significantly reduced the adjusted degree of the initial issue price, but not the partial revision period. Second, The revision of the rules results in the reduction of CAR(cumulative abnormal returns), and the full revision period also results in the reduction of CAR in the interaction between the full revision period and the adjusted degree of the offer price, but not the partial revision period. this reached a conclusion that the full revision of underwriting rules in 2007 significantly influences on the adjusted degree of the initial issue price, cumulative abnormal returns of IPO when listed on Korean stock market, and the factors determining the initial issue price of IPO. These robust results imply very important tips not only to the IPO policy maker in selecting IPOs rules for the purpose of improving underwriting rules, but also to the IPO issuers for the purpose of setting the appropriate price of IPOs in the issuing markets.