A wiper motor (10) comprises: a motor body (11) comprising a motor case (13) rotatably supporting an end of the motor shaft (17) in the axial direction thereof; a reduction mechanism (26) reducting the speed of rotation of the motor shaft (17) and transmitting the rotation having the reduced speed to a worm wheel (35); and a motion conversion mechanism (29) converting the rotational motion of the worm wheel (35) into a rocking motion and transmitting the rocking motion to an output shaft (28). The position of the output shaft (28) is set up that the axis (C1) of the output shaft (28) is closer to the motor case (13) than the axis (C2) of the worm wheel (35) and farther from the axis (C2) of the worm wheel (35) than the axis (C) of the motor shaft (17).
