A radiation member (10) for a semiconductor device is formed by an aluminum alloy member having a low thermal expansion aluminum alloy section (11) and a high radiation aluminum alloy section (12) which are joined and integrally formed with each other. A semiconductor device (13) is carried on the major surface of the low thermal expansion aluminum alloy section (11). The low thermal expansion coefficient aluminum alloy has an average thermal expansion coefficient of not more than 17x10-6/ DEG C. The high radiation aluminum alloy is larger in thermal conductivity than the low thermal expansion aluminum alloy.
