To efficiently cool a rotor of an axial permanent magnet motor, especially a permanent magnet.

An air channel 36 where a fluid such as air flows is formed between permanent magnets 34 constituting the magnetic pole of a rotor 30. The air channel 36 is provided almost in the radial direction of the rotor 30, and the fluid in the channel flows under the action of a centrifugal force when the rotor rotates. Thus, cooling is carried out near the permanent magnet, which heats more, inside the rotor, and the generated heat is promptly exhausted, while the heat radiation area of the rotor increases for more efficient cooling.