To reduce the number of parts, and to easily introduce automatic assembling at assembling a motor, in the diaphragm pump.

An outer circumferential surface of a motor 2 includes a plurality of recesses 7 that are simultaneously formed when an abutting portion 3a for mounting a permanent magnet 6 at a predetermined position of a yoke 3 is formed by indentation. The motor 2 is fitted into a diaphragm holder 20 and pushed in an axial direction (direction shown by an arrow A) of the diaphragm holder 20. By making the recesses 7 engaged with projections 20c of the diaphragm holder 20 while elastically deforming the diaphragm holder 20, the motor 2 is mounted to the diaphragm holder 20.