PURPOSE: To obtain a metal-base composite material in high yield, by previously coating a preformed body consisting ceramics fibers, etc., with a material having a melting point lower than that of the above preformed body and by forming the preformed body by diffusion joining so as to improve strength and also to inhibit shrinkage and prevent breakage at the time of pressure infiltration with molten-metal matrix.

CONSTITUTION: The surface of a reinforcement constituting a preformed body and consisting of ceramics fibers, whiskers, or grains is coated with a material having a melting point lower than the melting points of the principal components of the reinforcement. Subsequently, at the time of forming the preformed body out of the coated reinforcement, the reinforcement is subjected to diffusion joining at a relatively low temp. by means of heating at a temp. of the melting point of the above-mentioned material or above. Accordingly, the deformation, shrinkage, cracking, etc., of the preformed body are not caused at the time of subjecting the above-mentioned reinforcement to pressure impregnation with molten-metal matrix, and the metal-base composite material in which the reinforcement is uniformly disposed can be obtained.