An impeller is provided with a rotating shaft rotatably supported at the upper and lower ends thereof by an upper bearing and a lower bearing, a plurality of vanes connected to the rotating shaft on the inner circumferential edge side thereof, an annular coupling portion connecting outer circumferential edges of the vanes, and driven magnet portions provided in a lower portion of the annular coupling portion. The rotation of a rotor is transmitted to the impeller through magnetic coupling between the driven magnets and drive magnets provided to the rotor. The upper edge of each of the vanes has a bend point, and an angle α formed by a peripheral upper vane edge and an angle β formed by a central upper vane edge relative to the downward direction of the rotating shaft are both acute angles and have a relationship of α<β. An inner wall surface of a housing in a region opposed to the upper edge of the vane has a shape following the upper edge of the vane.
