An electronic device, including a circuit board, a communication chip, a first heat sink, a fixer and a shielding mask, is provided. The circuit board has a frame having an opening and several rims surrounding the opening. The communication chip, disposed on the circuit board, is located in the opening of the frame. The first heat sink, disposed on the communication chip, has a first surface facing and contacting the communication chip. The fixer is fixed into the circuit board and the first heat sink, such that the first heat sink remains contacting the communication chip. The shielding mask, disposed on the circuit board, includes a cover and several side boards. The cover covers the communication chip and the first heat sink, such that the cover contacts a second surface of the first heat sink. The side boards are opposite and connected to the rims in parallel.