An electronic device includes a case, a mother board, a fixing component, a fastening module and an interface card. The fastening module comprises a circuit board, a first connector, a second connector and a fastening component. The circuit board is fixed to the fixing component. The circuit board has a sliding groove. The first connector is fixed to a top surface of the circuit board. The second connector is fixed to a bottom surface of the circuit board. The fastening component includes a sliding portion, a first fastening portion and a second fastening portion. The first and second fastening portions are fixed to the sliding portion. The sliding portion is slidably disposed in the sliding groove to adjust a distance between the first fastening portion and the first connector and a distance between the second fastening portion and the second connector.