In a compact motor 1 comprising a cylindrical permanent magnet 13, which is affixed to the inner surface of a hollow cylindrical yoke 12, and an armature core 22, which is provided at the interior of the permanent magnet 13, the armature core 22 comprises three slots 29 disposed at a uniform pitch, the permanent magnet 13 is bipolar-magnetized, and each magnetic pole has a maximum magnetic flux density value P in a range of 40° to 50° from the center at both sides of the magnetic pole, the maximum value P being within the range of 1.3 times to 1.8 times the magnetic flux density at the center of the magnetic pole.