The invention provides a vibration reduction device for a vehicle seat that can reduce forward/backward vibration when the vehicle is stopped with the engine idling. The vibration reduction device includes a weight mounted through an elastic body in the seat back or the headrest of the seat. A vibration damping device for a vehicle seat. The weight having a predetermined weight therein is mountedon the frame of the seat of the vehicle by means of a resiliently bendable elastic bracket to be able to swing back and forth in the vehicle. The elastic bracket reduces the front and rear vibration of the seat by bending back and forth when the weight is swung.