Provided is a rotating electrical machine including a housing in which a flow passage of cooling liquid can be easily formed and airtightness and productivity are high. A rotating electrical machine is configured to include a housing which is provided with a part of a flow passage of cooling liquid, a stator which is disposed on an inner circumferential side of the housing and includes a stator winding, and a rotor which is rotatably supported to an inner circumferential side of the stator with a gap between the stator and the rotor and the flow passage of the cooling liquid includes an annular groove having an open surface on at least one side of an axial direction of the housing and a plate provided to cover the open surface. Preferably, the housing and the plate are configured to be joined by welding or an adhesive material. In addition, roughening processing or chemical processing may be performed on parts of the housing and the plate and the housing and the plate may be configured to be joined by a resin.