The recent development of information technologies due to advent of a new generation of semiconductor devices has brought us serious problems associated with high heat generation density. Conventional cooling methods such as fin heat sinks with blowing fans may not be sufficient to solve such serious heat related problems. Thus, in this study, we propose a new kind of heat sink as a solution to the problems, namely, a pin fin heat sink filled with metal foams. A series of exhaustive experiments have been conducted to confirm heat transfer enhancement as results of extended surface area and fluid mixing due to the presence of metal foams. Theoretical consideration has also been made so as to elucidate such heat transfer enhancement mechanism.