PURPOSE: To improve the productivity by roll forming an aluminum alloy-made ringed member to form a rim member, setting the aluminum member, heating, supplying a molten metal in such a condition and integrally forming a disk member and the rim member.

CONSTITUTION: In a first process, by roll-forming the aluminum alloy-made ringed member with a gap between at least one pair of the rolls, the prescribed shape of a rim member 14 is formed. In a second process, the rim member 14 is set to the prescribed upper die 15 and the lower die 16, and the rim member 14 is heated. In a third process, by supplying the molten aluminum alloy into the metallic mold in the condition of heating the rim member 14, the prescribed shape of the disk member 18 is integrally formed with the rim member 14. Thus, the shortage of the manufacturing time, the improvement of the yield, etc., can be executed, and the productivity is improved and the high quality product solving a problem in the strength can be obtd.