An electronic device includes a housing, a heat source located inside a casing, and a heat dissipation device disposed inside a casing. The heat dissipation device is in thermal contact with the heat source. The heat dissipation device includes a casing having a heat dissipation material. The heat dissipation material includes 15 to 30 volume percent of multiple copper materials, 50 to 85 volume percent of a phase change material, and 15 to 20 volume percent of air. The casing has a surface being in thermal contact with the heat source. A central area and an outer ring area are defined on the surface. The outer ring area surrounds the central area. A geometric midpoint of the central area and a geometric midpoint of the surface are overlapped. The heat dissipation device absorbs heat generated by the heat source located in the central area through thermal conduction.