New seismic dampers named Buckling-Restrained Rippled Plate (BRRP) dampers have been developed. BRRP is similar in shape to BRB (Buckling-Restrained Brace), but its core member is a 2D rippled plate instead of a 1D narrow flat plate. BRRPs are intended to be used as stoppers, setting at the edges of a girder-type bridge, which will act as stiff elastic bearings for Level 1 earthquakes, while for Level 2 earthquakes as energy dissipating seismic dampers. The target performance of BRRPs is such that they can withstand the earthquakes exceeding Level 2 earthquakes (say, 1.5 times larger than Level 2 earthquakes). The elasto-plastic behavior of BRRPs has been investigated using cyclic loading tests and analyses to acquire the fundamental knowledge of their performances.