Rotating electrical machine

An annular rotor-side circumferential wall is provided to stand on an end surface of a rotor. An arc-shaped case-side circumferential wall is provided to stand on an inner wall surface of an end cover facing the end surface of the rotor, in close proximity to the rotor-side circumferential wall. A coolant reservoir for receiving and storing a coolant is formed by the end surface of the rotor, the inner wall surface of the end cover, the rotor-side circumferential wall, and the case-side circumferential wall. A rotor core has a coolant flow passage extending and penetrating in a direction along a rotational axis. The coolant flow passage is arranged to be open with respect to the coolant reservoir. The coolant flowing from the coolant reservoir into the coolant flow passage cools the rotor core from inside.