PURPOSE: To improve the strength of a composite material and to reduce the dispersion of strength by specifying the amount of SiO2 contained in a reinforcement.

CONSTITUTION: In an SiC reinforced light alloy composite in which the whiskers and/or grains of SiC are used as a reinforcement, the amount of SiO2 contained in the above reinforcement is regulated to 0.1-4.0% by weight. By specifying the amount of SiO2 as mentioned above, wettability between the SiC whiskers, etc., and the light alloy matrix can be improved while maintaining the strength of the SiC whiskers, etc., and as a result, the strength of the composite is improved and the variance of strength is reduced. When the above SiO2 content is less than 0.1%, the wettability between the SiC whiskers and the light alloy matrix is deteriorated, and further, deterioration in the strength of the composite and the large variance of strength are brought about with the above deterioration in wettability. Moreover, when SiO2 content exceeds 4.0%, the strength of SiC whiskers, etc., becomes insufficient, and, since SiO2 becomes the origin of the cracking of the matrix, the strength of the composite is deteriorated.