To provide a vibration control device for a building structure, which is equipped with an inexpensively and simply manufacturable base member capable of reducing weight while maintaining necessary strength.

This vibration control device for the building structure comprises: the base member 1 which is fixed to the building structure in the state of being rectangularly assembled from two cross beams 11 juxtaposed at a distance and four vertical beams 15 arranged between both the cross beams 11; a plurality of spring members 2 which are attached to the base member 1; and a square member 3 which is elastically supported by the spring member 2 and arranged on the base member 1. The base member 1 is composed of the cross beam 11 in which webs 12a of two beam materials 12 formed with a U-shaped cross section by bending a plated steel plate are fastened and fixed in the state of being superposed on each other, and the vertical beam 15 in which a connecting portion 15d formed with a U-shaped cross section by bending a plated steel plate and provided at both longitudinal ends is fastened and fixed to the web 12a of the cross beam 11.