A portable electronic device includes a main body, a housing and a protective cover. The main body includes a keypad. The housing is attached to the main body. The housing defines a receiving space and two guiding grooves. The two guiding grooves are positioned at two opposite sides of the receiving space and communicating with the receiving space. The protective cover includes two rails respectively engaged in the two guiding grooves. The protective cover is slidable in the receiving space along the guiding grooves to cover or expose the keypad.