To surely prevent the chattering vibration of a wiper, and surely restrain the occurrence of chattering vibration without hurting an user's feeling.

In the prevention device 10 for the chattering vibration of a wiper, when the constituent of chattering vibration taken out of a vibration sensor 5 exceeds a reference value, a control signal reverse in phase with the constituent of chattering vibration is generated so as to be synchronized with the constituent of chattering vibration, and a control signal synchronized as mentioned above, is combined with a driving signal from a wiper control unit 20 so as to be outputted to a wiper motor 3. By this constitution, the wiper motor 3 is actively controlled in such a way that force reverse in phase with chattering vibration is applied to the wiper motor, so that chattering vibration is thereby canceled. In the device as mentioned above, any user's feeling is prevented from being hurt by a step against user's intention such as a proposal and the like where the wiper motor 3 is increased in torque so as to allow a wiper to be driven at the high speed, and chattering vibration can thereby be surely suppressed under any condition.