PURPOSE: To radiate the heat, generated inside a stator coil, to the outside efficiently by inserting the heat-absorbing side of a heat sink into between laminated iron core blocks, and attaching the heat radiating side to the outside of the laminated iron core block.

CONSTITUTION: A stator coil 2 and a heat absorbing fil 11, in close contact with a laminated iron core block 1, are mounted between a laminated iron core block 1 and a laminated iron core block 1. A through hole not shown in the figure is provided in this heat absorbing fin 11, and the heat absorbing part 15 of a heat pipe 10 is inserted into this through hole so as to absorb the heat inside the stator coil 2. On the other hand, the heat radiating part 14 is attached to the outside of an outlet pipe 16 connected to an outer duct 4, whereby heat is transmitted to conductive fluid through the outlet pipe 16. This way, it is so arranged that the heat inside the stator coil 2 may be collected efficiently in the fluid flowing inside the outlet pipe 16 making use of the evaporating and condensing actions of the heat medium inside the heat pipe 10, so heat generation of the stator coil can be enlarged, whereby a small- sized and large capacity of electromagnetic pump can be obtained.