Vibration generating means

Two vibration disposed in parallel with the rotary shaft of the eccentric weight is provided generating device, in order to reduce the required motor capacity and power consumption to the two rotary shaft (31a), (31b) driven independently embodiment provided with an electric motor (Ma), (Mb), and the rotational drive control means is configured to: when starting the two rotary shaft (31a), either one of the rotating shaft (31b) is started, the rotary shaft rotation driving state after the transition to a stable state, the other starts rotating shaft.