To suppress noise which is generated with the rotation of a rotor, in a motor having the rotor and a stator accommodated in the rotor.

The motor M includes: the rotor 2 having a salient 8 which is radially salient in the radial direction perpendicular to a rotation axial center, and a magnetism receiving part 9 extending to the rotation axial center at the protrusive end of the salient 8; coils 5 which are accommodated in the rotors 2, and excited in the axial direction; and the stator 1 having a plurality of stator cores 6 which accommodate the coils 5, and can form a magnetic path between the magnetism receiving part and the stator. In the motor, recesses 6y are formed at centers in radial directions of faces of internal peripheral sides of the stator cores 6.