An insert including a taper is covered with a molten metal. A metal molded product with the insert joined thereto is generated by semi-cooling the molten metal to a press-fitting temperature which is higher than a recrystallization temperature of the molten metal and lower than a melting point of the molten metal. A fitting hole which is filled with the insert is formed in the metal molded product. The taper is fitted into the fitting hole. An undercut is not formed in front of a tip of the taper. The insert is press-fitted into the fitting hole while pressing and extending the fitting hole with the taper in a thinning direction of the taper at a press-fitting temperature. The metal molded product is further cooled with the press-fitting maintained.