A heat spreader includes thin films opposite to each other; cooling liquid filling an internal space between the thin films; and a vibration generating means for vibrating the liquid. Accordingly, the heat spreader has excellent heat spread performance compared to a conventional heat spreader, so can have an ultra slim type structure. Also, the heat spreader has excellent heat spread performance regardless of a direction of gravity, and a space between the thin films is sealed in a state of an atmospheric pressure, to maintain the improved heat spread performance for a long time.