PURPOSE: To reduce the number of component parts, and to stabilize the control of a motor by integrally molding a protective cover by a stator yoke.

CONSTITUTION: A driving coil 9, a speed detecting sensor 4, a flexible wiring 7 and insulating paper 2 for the wiring 7 are held to a driving coil yoke 15, and the yoke 15 is fitted to a motor flange 1 and the yoke 15 and the motor flange are sealed. A magnet rotor yoke seat 8, a magnet rotor 10, a rotor yoke 11 and a magnet 3 for detecting speed are held to a motor output shaft 5, thus forming a body of revolution. In this case, the rotor yoke 11 is varied partially, and a driving coil 2 is disposed to one part of a protective cover and the protective cover and the driving coil yoke 15 are shared. The driving coil yoke 15 is molded in L size to the height l of the speed detecting sensor 4, and l<L holds, thus stabilizing the accuracy of built-in of the sensor 4.