A heat dissipating device for dissipating the heat produced by a heating element is disclosed. The heat dissipating device includes a fixing assembly, two moving assemblies and an elastic assembly. The fixing assembly has a thermal conductive member. Each moving assembly has a mass body and is relatively moveable with respect to the fixing assembly. The two moving assemblies are disposed on two opposite sides of the fixing assembly, respectively, and each moving assembly forms a moving space with respect to the fixing assembly. The elastic assembly connects the fixing assembly to the two moving assemblies.