A heat sink and an electronic apparatus using the same are disclosed. The heat sink comprises a fin structure and a fastening assembly; the fastening assembly comprises an adjustable positioning member, an elastic member, and a hooking member, the elastic member being disposed between the hooking member and the fin structure such that the adjustable positioning member combines the hooking member, the elastic member, and the fin structure; wherein the hooking member may secure the heat sink onto an electronic component, and the adjustable positioning member may be used to adjust the tightness between the heat sink and the electronic component.