Blades are connected to the surface of a disk and slots are formed in the surface of a shroud, which is opposite from the other surface of the shroud where the blades are to be welded. The blades are arranged on the opposite surface from the slots and a laser beam is applied from the surface in which the slots are formed, to weld the shroud and the blades. Components are installed on the surfaces of the slots on the opposite side from the blades after the blades and the shroud in which the slots are formed are welded. Alternatively, the slots are filled with a material different from that of the shroud, such as a resin. With this configuration, distortion caused by welding heat can be reduced without degrading the fluid performance.