A portable electronic device provided with a function which is required to be preset before supplying electric power to the device is provided. The device comprises a switch, an operating member, and a battery chamber. The switch is used to preset the function. The operating member is used to switch the switch. The battery chamber is for loading at least one battery. Further, the operating member is arranged inside the battery chamber and the operating member is concealed with the battery when the battery is loaded inside the battery chamber.