A heat dissipation device attached to a top surface of an electronic device mounted on a printed circuit board, includes a heat sink and a retainer securing the heat sink onto the electronic device. The retainer includes a frame, a plurality of baffle walls and protrusion posts extending downwardly from the frame. Lower ends of the baffle walls of the retainer extend downwardly through the heat sink and engage with engaging edges of the electronic device. The heat dissipation device is further provided with a plurality of elastic members which respectively surround the protrusion posts of the retainer and are compressed between the retainer and the heat sink, thereby pushing the heat sink downwardly toward the electronic device.