Provided are a heat sink and a memory module using the heat sink. In one embodiment, the heat sink includes a first and second guide pin respectively disposed in first and second heat spreaders placed around an object to be cooled. The first and second guide pins help prevent misalignment problems from occurring between the first and second heat spreaders, as well, as helping prevent the first and second heat spreaders from contacting each other when the first and second heat spreaders are pressed by pressure applied from the outside.