PURPOSE: To reduce shaft seal for a pump integrated with an electric motor which is used for a rocket liquid fuel booster by installing a dielectric motor rotor in a manner that It is integrated with the outer periphery of an impeller in a casing, and locating a stator outside the casing in opposition to the rotor.

CONSTITUTION: A dielectric motor rotor 1 is installed in the outer periphery of an impeller 5 in a manner that it is integrated with the impeller 5. The rotation shaft 3 of the motor is supported to a casing 2 using a bearing 6. In addition, a stator 4 is installed outside the casing 2 so as to drive the rotor 1. This constitution perfectly separates the inside where fluid is flowing from the outside and the magnetic force of the stator 4 causes the rotor 1 to generate repelling power to rotate the rotor 1 and thus the impeller 5. As a result, this device works as a pump.