PURPOSE: To provide a reinforcing effect by impregnating clearances among fibers with matrix metals by bundling inorg. fibers with metals which dissolve to a certain extent in the matrix metals and have prescribed m. p. thereby integrating the fibers and the metals.

CONSTITUTION: Metals (lithium, sodium, magnesium, etc.) which have m. p. lower than m. p. of matrix metals (magnesium, aluminum, copper, etc.) and ≥50°C, and have the solubility in the matrix metals at temp. higher by ≥10°C than the m. p. of the matrix metals and 10vol% are prepared. Inorg. fibers are beforehand bundled by 1 ≥ kind of such bundling metals. The bundled fiber bundles are mixed with the melt of the matrix metals to penetrate the matrix metals in the clearances among the fibers whereby the fiber bundles and the matrix metals are integrated.