PURPOSE: To decrease magnetic core space volume with magnetic flux and to reduce an iron loss so as to obtain a large output torque by providing constitution such that mounting space of an excitation coil is increased to a maximum in the case of an external diameter of an electric motor in a predetermined value.

CONSTITUTION: 26 salient poles 1a, 1b,... are provided in a peripheral part of a rotor 1 and opposed to magnetic poles 16a, 16b,... through a space of about 0.15mm. A width of the magnetic poles 16a, 16b,... is equally formed to a salient pole width and protruded to the inside from a magnetic core 16 to space apart the magnetic poles 16a, -16a by four times the salient pole width and also the magnetic poles 16b, -16b, placed in a symmetrical position, by four times the salient pole width. An excitation coil of the first phase is formed of excitation coils 17a, -17a, 17d, -17d. Further, recessed parts 24a, 24b,... and deletion parts are formed in the peripheral part of an armature 16.