To provide an Al-alloy disk brake and its manufacturing method, which has a sliding part made of a metal group composite material having excellent wear resistance, heat resistance and thermal crack resistance and can easily be machined.

A sliding part is made beforehand so as to have a necessary shape using a metal group composite material having excellent brake performance. This sliding part is put in a casting mold, and then molten Al-alloy is poured into the mold. Consequently, a brake disk, which is light, can bear a heavy load and can easily be machined in manufacturing, and its manufacturing method can be obtained.