There is provided a portable electronic device capable of being immediately operated without the use of a battery even when the battery reaches exhaustion. An electricity generating unit 131 is embedded in the portable electronic device. The electricity generating unit 131 has a mechanism to pull out a pull line 113 wound around a pulley 135 to wind up a spiral spring 133 and a mechanism to transfer torque occurring when the spiral spring 133 is released and to rotate the motor at high speed. An output voltage from the motor 142 is adjusted and smoothed by a constant voltage circuit and is directly supplied as power to power consuming components. The portable electronic device connecting two flips can wind up the spiral spring 133 by opening and closing the two flips.