To provide a light metal-based composite material excellent in strength, toughness and further having a damping capacity (internal friction), and to provide a method for production thereof.

In the light metal-based composite material, a reinforcing phase consisting mainly of the nanocrystal structure of an iron-based alloy is dispersed in a parent phase comprising a light metal, and an intermetallic compound is formed between the parent phase and reinforcing phase. The method for producing the composite material includes a mixing process of mixing the light metal with a reinforcing material consisting mainly of the nanocrystal structure of the iron-based alloy, and a sintering process of sintering the mixture obtained by the above mixing process. In the sintering process, the intermetallic compound phase is formed between the parent phase of the light metal and the reinforcing phase of the reinforcing material.