A portable electronic device includes a housing, a plurality of buttons mounted on the housing for operating the portable electronic device, a power supply received in the housing for supplying working electric power to the portable electronic device, and a generator unit. The generator unit includes a plurality of magnetic components mounted on the buttons and a plurality of windings received in the housing and electronically connected to the power supply. Thereby induced currents for charging the power supply are generated when the magnetic components are moved with the movements of the operated buttons.