Abstract: A device for limiting the direction of rotation of a synchronous motor includes a gear connectable to a rotor of the motor for being rotated. A shaft rotatably supports the gear in such a manner that the gear is movable along the axis of the shaft. A pair of fixed members are fixed to a casing and support the shaft. The gear is interposed between the pair of fixed members, and one of the fixed members has a first engaging portion on a surface thereof facing the gear. A first projection is integrally formed on a surface of the gear facing the one fixed member, the projection being engageable with the engaging portion when the gear is rotated. The projection is engageable with the engaging portion to move the gear along the axis of the shaft to allow the rotation of the gear when the rotor is rotated in a normal direction. The projection is brought into abutting engagement with the engaging portion to prevent the rotation of the gear when the rotor is rotated in a reverse direction.