To obtain a fiber-reinforced composite material different in mechanical or thermal physical properties between the inner part and outer part by subjecting a fiber structure comprising a reinforced fiber and a non-reinforced fiber to physical or chemical treatment before or after impregnating into a matrix resin.

A fiber structure such as a one-way woven fabric or a two-dimensional woven fabric or a three dimensional woven fabric or network-like structure is formed by using a reinforcing fiber such as carbon fiber and a non-reinforcing fiber such as aramid fiber. The fiber structure is subjected to high temperature heating treatment before or after impregnating into a matrix resin such as phenol resin and the aramid fiber as the non-reinforcing fiber is substantially decomposed to provide the objective carbon/carbon composite.