PURPOSE: To generate strong electric fields both in a magnetic pole for drive and a magnetic pole for detecting speed without generating field spots in both magnetic poles by using a magnetizer consisting of a pole magnetizing section for drive, in which several comparatively large-sized magnetic poles are arranged annularly, and a pole magnetizing section for detecting speed in which a large number of comparatively small-sized magnetic poles are disposed circularly.

CONSTITUTION: An annular permanent magnet 1 to be magnetized, a cuppy yoke 4 and an auxiliary yoke 12 are placed on a magnetizer. When currents are caused to flow simultaneously through a magnetic coil 10 wound on a central-section annular yoke 8 and a magnetic coil 7 wound on an outer- circumferential section annular yoke 5, the central-section annular yoke 8 and the outer-circumferential section annular yoke 5 are each magnetized, and the contact surface of the annular permanent magnet 1 to be magnetized placed onto the magnetizer can be magnetized. Accordingly, a magnetic pole 2 for drive and a magnetic pole 3 for detecting speed are magnetized at the same time, thus generating strong magnetic fields both in the magnetic pole 2 and the magnetic pole 3 without generating field spots in both magnetic poles.