Motor provided with rotor

A rotor includes: a shaft; a rotor back yoke having a through hole defined in an axial center through which the shaft is inserted, the rotor back yoke being integrally and rotatably connected to the shaft; and magnets fixed to an outer peripheral surface of the rotor back yoke, the plurality of magnets being disposed with magnetic poles of different polarities being arranged alternately along a circumferential direction. The rotor back yoke includes a plurality of first cutout portions provided at predetermined intervals in the circumferential direction and extending from an inner peripheral surface of the rotor back yoke outward in a radial direction. Each of the plurality of first cutout portions extends along an axial direction, from one end surface to the other end surface of the rotor back yoke.