PURPOSE: To dispense with shaft seal so as to dissolve friction loss and wear caused by sliding motion between a shaft and the seal and to prevent the leak of liquid by mounting the rotor of an induction motor to the outer periphery of a rotatably supported impeller, and disposing a stator inside a casing, face to face with the rotor.

CONSTITUTION: In this pump, the rotor 1 of an induction motor is mounted to the outer periphery of an impeller 5, integrally with the impeller 5, and the impeller 5 integral with the rotor 1 is integrated into a casing 2, together with a bearing 6, a rotary shaft 3, and the like. Inside the casing, a stator 4 is fitted face to face with the rotor 1, and the inside where a fluid passes is completely separated from the outside by the casing 2. When magnetic force is generated by the stator 4, resiliency is generated to the rotor 1, against this magnetic force, so that the rotor 1 is rotated. At the same time, the impeller 5 is also rotated to perform pumping action. Accordingly, there is no need to pass the rotary shaft 3 through to the outside of the casing 2 to drive the impeller 5, so that shaft seal can be dispensed with.