A magnetron includes an anode cylinder extending in a cylindrical shape along a central axis and a plurality of plate-like vanes at least each one end of which is fixed to the anode cylinder, extending from an inner face of the anode cylinder toward the central axis, in which the anode cylinder includes refrigerant flow paths for directly applying a refrigerant to the plate-like vanes. The refrigerant flow paths 111 are openings formed so that end surfaces (joint end faces of the plate-like vanes) of the plate-like vanes are exposed, which allow the refrigerant to directly contact the plate-like vanes.