To ensure visibility of the driver by continuing operation of a wiper even upon failure of a sensor for a motor rotation pulse. [MEANS FOR SOLVING PROBLEMS] A wiper arm is reciprocated for wiping by rotating a motor forward and reversely, and the operation of the wiper arm is controlled according to an absolute position signal outputted when the wiper arm exists at a predetermined position and a motor pulse outputted as the motor rotates. Input of the motor pulse is recognized (S32). When an abnormality occurs in the motor pulse, the motor is rotated forward for a predetermined time at a constant duty (S33). After a forward driving, the motor is rotated reversely for a predetermined time at a constant duty (S34). Consequently, the wiper arm continues reciprocal wiping operation even when a relative position signal is abnormal, thus ensuring visibility of the driver. Forward/reverse operation is continued for a predetermined time, and then the motor is stopped (S35, S36). |