A heat dissipating device of the present invention includes a heat sink (20) and two locking devices (10) for securing the heat sink. The heat sink includes a base (22) for contacting an electronic component. Each locking device includes a spring member, a post (12) and a sleeve (18). The spring member elastically rests on the base. The post extends through the sleeve. The post has one end engaging with the spring member, and an opposite end thereof extending beyond the sleeve for locking the combination. The sleeve has one end tightly grasping the post, and an opposite end thereof preventing the locking device from departing from the heat sink.