PURPOSE: To keep the reliability of a portable electronic device and to prevent the reduction in an operation available time by providing a cooling means employing a solar battery for its drive power supply to the cooler to cool a heat generation part to be cooled in the portable electronic device.

CONSTITUTION: The electric energy outputted from a solar battery 50 is proportional to the energy of the incident sun-ray. Thus, when a portable telephone set is used under direct sun-ray, the maximum electric energy is obtained from the solar battery 50, the forced cooling effect of active circuits 10, 20 by a fan 41 is maximized and the reliability of the portable telephone set is maintained. Furthermore, the fan 41 is driven by using the electric energy obtained by the solar battery 50 to avoid depletion of a battery power supply 30 for the active circuits 10, 20 attended with the forced cooling. Thus, the operation available time of the portable telephone set in the talking state and the standby state is ensured.