To simply and certainly carry out a mounting of a motor yoke to a shaft and to stabilize a strength of a mounting part of the motor yoke in the case where a motor structure part is particularly compact in a fan in which the motor yoke is mounted to the shaft supported by bearings and a stator iron core is disposed at the inside of the motor yoke.

A stepped portion 19 of which an end surface side has a small diameter is formed on one end of a shaft 6 and a center part of a motor yoke 11 is press-inserted thereto. The motor yoke 11 is directly mounted to the shaft 6 by calking-fixing the motor yoke 11 after press-insertion to the stepped part 19. Thereby, a boss conventionally provided between the shaft 6 and the motor yoke 11 is not required to simplify a structure.