In a case of the embodiment of FIG. 5, three N-pole permanent magnets 30 are inserted into the rotor 20, and the iron core portion 22 between the N-pole permanent magnet 30 and the N-pole permanent magnet 30 is magnetized to the S-pole, thereby forming a consequent pole. Therefore, even when the plurality of permanent magnets 30 having the same polarity are used in the rotor 20, the same magnetic field as that of a conventional motor using a plurality of permanent magnets having different polarities is formed.

The number of the magnetic poles (or the magnetic pole number) of the rotor 20 includes the number of the permanent magnets 30 and the number of consequent poles 22. For example, when three permanent magnets 30 are provided in the rotor 20 as illustrated in FIG. 5, three consequent poles 22 are formed between the three permanent magnets 30, so that the number of the magnetic poles of the rotor 20 is six. Therefore, in the interior permanent magnet motor 1 according to the present embodiment, the number of the permanent magnets 30 provided in the rotor 20 is half the number of magnetic poles of the rotor 20.

The number P of magnetic poles of the rotor 20 used in the interior permanent magnet motor 1 according to an embodiment of the disclosure may satisfy the following formula.
P=2N

Here, N is a natural number and satisfies 2≤N≤8.

Therefore, the number of the permanent magnets 30 provided in the rotor 20 is P/2.