We proposed the design concept for steel shear panel damper. We introduced the design requirements for width-to-thickness ratio of shear panel damper’s flange. To show the validity of the design requirements, we performed the elastic buckling analysis and geometrically and material non-linear finite element analyses on simply supported three edge and free in the other edge of plate. Also, to show the accuracy of analytical results, we performed loading tests on short H-shaped steel member. From those results, we showed the validity of the proposed design requirements for S.P.D.'s flange width-to-thickness ratio.