To provide a copper composite material which has excellent low thermal expansibility and high thermal conductivity as a heat radiation board for a semiconductor device.

In the copper composite material, a porous sintered body obtained by sintering an inorganic substance whose thermal expansion coefficient is small than that of copper is impregnated with a copper alloy containing 0.4 to 2.5 wt.% O (oxygen) in the ratio of 20 to 60 vol.%. In this way, low thermal conductivity and high thermal expansibility can be obtained.