IWC (International Whaling Commision)become a buraue pointed by United Nations to concern at Whaling affairs based on International Convention for Regulation of Whaling (ICRW) that signed in 1931. However, his roled was inquired when IWC face the slaughter of dolphins in Taiji, Japan. Dolphins are included into small cetacean family. IWC can’t stop the case so that indicates the inectivity of IWC. This study will explain the factors that influence inectivity of IWC on stopping the slaughter of Dolphins in Taiji, Japan in a rzim efectivity side. By using a literature study and data analysis, The conclusion obtained in this study support the hypothesis that The inectivity of IWC’s rezim is influenced by Problem Malignancy and Problem Capacity in IWC.