In this study, a new type of rotary friction damper was proposed for the seismic retrofitting of building structures. The rotary friction damper was composed of 2 rotary friction pads, 3 steel plates, and 9-13 bolt holes. The clamping forces can be modulated for realizing the various yield moment of the damper. The test results indicated that the proposed damper showed stable hysteretic behavior and the designed yield moment could be obtained according to the applied torque and the number of bolt holes. Numerical analyses of a moment-frame retrofitted with the proposed dampers should that the seismic performance could be enhanced according to the yield moment of the dampers.