To provide an inexpensive fastening part structure of a motor to which a mounting bracket can be simply and reliably fastened and fixed by one bolt.

In the fastening part structure of the motor 20, the mounting bracket 30 is fastened and fixed to the motor 20 by the bolt 40. W-shaped wave-like surfaces 23a, 33a as recessed and projected surfaces are provided on the respective matching surfaces of the motor 20 and the mounting bracket 30, respectively, and the mounting bracket 40 is fastened and fixed to the motor 20 by one bolt 40 in a state where these W-shaped wave-like surfaces 23a, 33a are fitted to each other.