Vibration damping device and power transmission device

A vibration damping device comprising:

• a mass body disposed spaced apart from a center axis of a rotary shaft by a certain distance;
• and
• support portion that rotatably supports the mass body with respect to the rotary shaft and holds a posture of the mass body with respect to the center axis of the rotary shaft constant so that an inertial force of the mass body in a translational direction other than a direction of the rotation acts on the rotary shaft, wherein
• the support portion is constituted by a bearing provided between the rotary shaft and the mass body,
• the bearing is constituted by a plurality of rolling members each of which is rollably supported on an outer periphery side of the rotary shaft and rollably engaged with the mass body, and
• the plurality of the rolling members is a plurality of rows of radial ball bearings.