Urban renewal is usually hard to be arranged because of the high costs of integrating landowners. Local governments were often approved additional building bulk (ABB) as a key incentive for encouraging implementers to arrange urban renewal projects. It is thought that the more ABB are given, the more activeness the implementers will be. At the same time, urban renewal projects would be accelerated because of the extra floor areas arisen by ABB. However, ABB was criticized for its increasing public good burdens and leads to bad urban development. It is important to clarify the effects of approving ABB so as to evaluate the role that ABB plays in proceeding urban renewal. In this study, ABB is tried to be examined with the period between the urban renewal outline schemes were approved and the urban renewal plans were applied to local authorities in Taipei City. Besides, whether urban renewal implementers are benefited by ABB will also be checked so as to analyze the relationships between ABB and implementers.