A vibration control device for preventing buildings from collapsing in one or a few stories is proposed. The device which is mounted on two stories works to equalize the story drifts of the two stories. The shake table tests on a scaled three-story steel frame with the proposed device are conducted. The results show that the device is effective in promoting the uniform story drifts over the height of the test frame and in reducing the maximum story drift without an excessive increase of the response acceleration. The results of time history seismic response analyses indicate that the device can enhance the robustness of the structure against the variation of the strength and the stiffness of the story of the structure.