To solve the problem of a conventional parallel electromagnetic pump such that a liquid-form conductor is heated by currents due to its stay in the drive section of the electromagnetic pump when it requires static thrust, and there is a risk of a temperature rise getting over a tolerable value, in a electric power/mechanical power conversion system for driving an actuator by giving thrust to the liquid-form conductor by the electromagnetic pump.

Two units of equivalent electromagnetic pumps are connected to generate thrust in the same direction, and in a static thrust mode, a circulation flow of the liquid-form conductor is generated between the two units, and it is cooled with a cooler, and in large thrust-large flow mode, the two units cooperatively drive the liquid-form conductor in the same direction.