To provide a lightweight composite material having uniform and good thermal conductivity free from directivity.

The surface of vapor growth carbon fiber as a featherlike fibrous body vapor phase-grown using hydrocarbon such as benzene as a carbon feeding source and iron as neuclei in the presence of hydrogen, is formed with a silicon dioxide layer with a thickness of 0.01 to 0.1 μm by a sol-gel method, also, as the metal of the matrix, aluminum, various aluminum alloys, magnesium or magnesium alloys are used, and the metal is melted and press-impregnated into the fibrous layer via a filter made of porous ceramics.