To provide a motor cooling structure of a motor fan capable of sufficiently cooling a motor with an air flow passing through a blade, miniaturizing the motor, and improving durability of the motor.

This motor cooling structure of a motor fan comprises a motor 8, an approximate bottomed cylindrical boss part 4 fixed to a rotary shaft 9 of the motor 8, and a plurality of blades 5 projected outward in a radial direction from an outer periphery of the boss part 4. This structure has air introduction means for forming the air flow directed to the motor 8.