This invention provides an electronic device including a casing and a circuit board. The casing has an opening. The circuit board is located in the casing and at least includes a conductive layer and a surface insulating layer. The conductive layer includes a signal transmission portion and a static induction portion. The static induction portion is electrically disconnected with the signal transmission portion at the conductive layer, and the static induction portion is closer to the opening than the signal transmission portion. The surface insulating layer covers the signal transmission portion on the circuit board and exposes the static induction portion.