A portable electronic device includes a casing whereinside an accommodating space is formed, a signal terminal disposed on a lateral wall of the accommodating space, a stylus accommodated inside the accommodating space of the casing in a movable manner, a push-pop mechanism disposed inside the accommodating space of the casing for fixing the stylus at a corresponding position according to depth of the accommodating space whereinto the stylus enters, and a connector for inserting into the accommodating space of the casing so as to electrically connect with the signal terminal to transmit a corresponding signal.