To suppress dust production due to a contact of a taking-out preventing member which prevents the separation of a shaft and a sleeve of a motor with a part facing the member.

A motor 1 comprises a stator assembly 2 and a rotor assembly 3. A shaft 30 of the rotor assembly 3 is inserted in a sleeve 22 of the assembly 2, so that the rotor assembly 3 is rotatably supported. The drop-off preventing member 33 that prevents separation between the shaft 30 and the sleeve 22 is ring-like with its center as a central shaft 1a, which is fixed to the inner peripheral surface of a cylinder part 313 of a rotor hub 31 of the rotor assembly 3. The inside diameter of the drop-off preventing member 33 is smaller than the outside diameter of a lower surface 221b of a flange 221 formed at the sleeve 22, with an upper surface 33a of the drop-off preventing member 33 facing the lower surface 221b of the flange 221. Grease 60 is applied to at least one of the upper surface 33a of the drop-off preventing member 33 and the lower surface 221b of the flange 221.