MOTOR DEVICE

PROBLEM TO BE SOLVED: To achieve downsizing and weight saving while preventing reduction in output torque in a low-rotation number region.SOLUTION: A motor device comprises: a yoke 24 with an oval cross section; four magnets 25 arranged in the vicinity of a connection part CN between each arcuate part 24a and each planar part 24b of the yoke 24; and an armature 26 freely rotatably provided at the radial inside of each magnet 25. A length dimension W1 between each arcuate part 24a along a radial direction of the yoke 24 between the respective magnets 25, and the armature 26, is set to be larger than a length dimension W2 between each planar part 24b along the radial direction of the yoke 24 between the respective magnets 25, and the armature 26. Thus, the yoke 24 can be thinned by multi-polarization while being miniaturized by making it in an oval shape, and the size and weight of the power window motor 20 can be reduced. Since the length dimension W1 is set to be larger than the length dimension W2, the magnetic resistance can be increased to reduce armature counteraction compared with the conventional art, and reduction in output torque in a low-rotation number region can be prevented.