The present disclosure provides an electronic device. The electronic device includes a casing and a detachable unit. The casing includes an opening. The detachable unit is selectively disposed in the opening. The detachable unit includes a recognizing element. The detachable unit is provided for the electronic device provided in the present disclosure. In addition to having an electromagnetic shielding effect, the detachable unit can further provide various different functions, such as cooling, storage, display, communication, and accommodation. A user selects different detachable units according to needs. Therefore, the electronic device provided in the present disclosure helps improve user experience.