To perform pump operation without separately using an electric motor by a method wherein fluid is introduced through the inlet of a sleeve by an impeller arranged in the sleeve, fluid is fed with a pressure through the outlet of the sleeve to effect pump operation.

A stator 3 is disposed on the inner peripheral surface of a housing 1 and a cylindrical sleeve 4 on the inner peripheral surface of which an impeller 5 is disposed is arranged on the axis of the stator 3. The sleeve 4 is rotatably supported at the housing 1 and a rotor 9 formed such that a rotor coil 8 is wound around the outer peripheral surface of the sleeve 4. The sleeve 4 is rotated together with the rotor 9 by a rotating magnetic field generated by a current fed to the stator 3. Fluid is introduced through the inlet 4a of the sleeve 4 by an impeller 5 arranged in the sleeve 4, and fluid is fed with a pressure through the outlet 4b of the sleeve 4 to effect operation of a pump.