To provide a floor vibration damping device effectively decreasing floor impact sounds at a low cost.

A plurality of floor vibration damping devices 1 are vertically arranged to a floor constituent member 4 as a structural body of a building. Each floor vibration damping device 1 constituted of heavyweight members 11 and elastic members 12 enabling the heavyweight members 11 to vibratingly support has a natural frequency decided from spring constants of the elastic members 12 and 12 and mass of the heavyweight members 11, and the natural frequency is around 63Hz. The floor vibration damping device 1 can be vertically hung down to the constituent member 4 of the floor through a mounting member 6.