PURPOSE: To obtain a composite aluminum casting which is lightweight and is improved in the strength of the required part by embedding a cast iron having through-holes by casting into the stress concentrating part of a casting consisting of an aluminum alloy as a base material.

CONSTITUTION: High stress concentrates to the rest part 3 of, for example, a body caliper base body 1 for a disk brake during the operation of a brake and since the Al alloy is used for the body 1 for the purpose of reducing the weight, the reinforcement of the strength is required. An insert 4 made of the cast iron provided with plural pieces of the through-holes 8 and formed to an L shape is thereupon embedded by casting into the part 3 of the base body 1 in the stage of casting said body 1. The L shape is designed in accordance with stress resistant design and the holes 8 are provided in order to improve the wettability with the base body 1.