To reduce the thickness of a vibration control device and arrange a brace on the back of the vibration control device.

A lower part connecting member 21 obtained by bending a sheet metal member into a U-letter shape includes a fixed part 40 formed at the bottom part of the U-letter shape so that it may be fixed to a lower beam 16, and a pair of mutually facing holding parts 42 erected from front and back sides of the fixed part 40 in a manner of facing the front and back faces of a lower part panel 22, respectively. The lower part connecting member 21 is formed to have a U-letter shape in vertical cross section when viewed from the side, and the mounting space in the direction of the thickness is made to be only a little thicker than the thickness of the lower part panel 22 and the dimension in the direction of the thickness is made to be small. Therefore, the lower part panel 22 is fixed to a front side (the area of the front-side half in the direction of the thickness) of an upper surface of the lower beam 16. A brace 28 is diagonally mounted on a rear side (back side) of the lower part panel 22.