To provide a maintenance device for an electric motor of a rolling stock to perform ordinary maintenance of an electric motor for a vehicle with the maintenance device mounted on the rolling stock (a present attitude state).

A maintenance device comprises a pair of support rollers 22 to support a wheel axle 1a driven by an electric motor in a state that a rolling stock is supported by two rails; a jack up device 24 to float only a corresponding wheel 1 from a rail by pushing upward the support rollers against a shaft spring; a rotational drive device 26 to rotate a wheel axle through rotation of the support rollers in a state that the wheel is levitated from the rail; and a maintenance truck 28 movable in a pit along the rail. This constitution levitates the wheel from the rail and supplies grease and/or performs grinding of a commutator by reversing the electric motor through reversing of the wheel axle.