2009年 8月日本民主黨（以下簡稱「民主黨」），在眾議院選舉 480 席中贏得 308席取得 執政，終結自由民主黨（以下簡稱「自民黨」）超過半世紀的執政。但是相隔三年多， 在 2012年 12月眾議院選舉，民主黨僅得到 57席，自民黨贏得 294 席重新取得執政。 民主黨的大敗，一般以為並不是因為自民黨很受到歡迎，而是因為選民對於民主黨的不 滿。事實上，民主黨執政時期，人民最大不滿就是民主黨的政見沒有落實。不僅如此， 民主黨政權的內閣法案通過率其平均遠低於戰後的內閣法案通過率。對於超過 300 席、 在眾議院掌有優勢民主黨，為什麼會推動法案不利？政策的僵局是怎麼造成的。本計畫 以為，民主黨的政策延宕，不是只是因為首相個人因素、內閣支持度不高，或是扭曲國 會所造成。本文以為是因為民主黨本身的制度所導致的政策僵局與有限的立法能力。 The Democratic Party of Japan (DPJ) came into power in 2009 promising to change Japan. However, policy stalemate has almost become a landmark of the DPJ government. Many policies which the DPJ campaigned on during the election of 2009 have been either disapproved or suspended. Moreover, the rate of passing bills has been low, much lower for the rate for the Hatoyama Cabinet and the Kan Cabinet when compared to the LDP-led cabinets. What explains such a low passing rate? Given the empowered cabinet resulting from administrative reforms since the 1990s, and the majority that the DPJ enjoys in the Diet, it is puzzling why the DPJ government has difficulties passing bills and pushing its own policy agenda. This project argues that the low support rate, weak leadership and the twisted Diet cannot explain the policy gridlock of the DPJ government since the LDP-led cabinets after Koizumi also faced a sharply declining support rate and a twisted Diet. Instead, we should investigate how the DPJ and the government interact because party support cannot be taken for granted. Moreover, this project argues that it is the system that the DPJ proposed where politicians are in charge of getting the party away from policy-making that has resulted in the intra-party conflict gridlock.