PURPOSE: To prevent the abrasion of a stator core and wedge by supplying the outer peripheral face of a rotor core with a coolant via air gap inside the stator core.

CONSTITUTION: A rotating machine-cooling liquid is supplied from the coolant supply hole 1d on the outer periphery side of a stator core 1 to the air gap G between the inner peripheral face of a stator core 1 and the outer peripheral face of a rotor core 6 through the coolant supply hole 1b in the stator core 1. In this case, the coolant effectively cools the inside of the stator core 1. Also, because the coolant is supplied from the stator core 1 side, the stator and rotor cores receive no unnecessarily large jetting force of coolant and a supply pressure can be adjusted suitably so that the air gap G can be provided with a coolant with appropriate pressure. Thus, the abrasion of the outer peripheral face of the rotor core 6 and abrasion of the inner peripheral face of the stator core 1 and wedge caused by the jetting pressure of coolant can be prevented surely.