A method manufactures a composite member that can exert a sufficient effect of reinforcing a metal part with a fiber-reinforced resin material when the metal part is obtained by bending a tubular member. The method firstly bends a tubular metal member having a plate-like outer wall extending in the longitudinal direction so that compressive stress acts on the outer wall to manufacture the metal part. Next the method prepares a plate-like metal plate. Next the method attaches a fiber-reinforced resin material to a surface of the prepared metal plate, the fiber-reinforced resin material including a fiber substrate containing reinforcement fibers having one orientation direction and impregnated with uncured thermosetting resin, followed by thermally curing of the thermosetting resin to prepare a reinforcement member. Next the method joins the metal plate of the reinforcement member to the surface of the outer wall of the metal part.