In the aftermath of the 1995 Hyogo-Ken Nanbu Earthquake in which many severe failures of bridge piers occurred, numerous studies have been conducted on ways to retrofit existing RC columns and piers. As a result of this research, it has been found that continuous fiber sheet offers a feasible means of retrofitting. Consequently, several design guidelines on the use of FRP sheets for retrofitting highway, railway and subway structures have been proposed in recent years. The JSCE (Japan Society for Civil Engineers) Concrete Committee on FRP Sheet, which was setup in 1998, has been commissioned to establish a new design method for seismic retrofit of bridge columns and piers. It seeks to unify all the existing guidelines on a performance-based design concept. This paper describes mainly the new design method of shear strength and ductility ·of retrofitted RC structures using FRP sheet. Design equations for shear strength and ductility are also presented.