NOVELTY - The device (30) has storage battery (16) to store electric power generated by solar cell (11). A charge-and-discharge control unit (31) is used to control power charging-and-discharging operation of battery. An air blower (33) is used to ventilate battery accommodating portion. A detection unit (32) is used to detect atmospheric temperature of battery accommodating portion. An air-blower control unit (34) is used to control air flow of air blower, to carry out electric power generation in solar cell, with respect to application of atmospheric-temperature conditions.    USE - Power supply device for supplying electric power to electric equipment such as camera, and mobile communication apparatus such as mobile telephone, used as local monitoring apparatus of remote place monitoring system for monitoring water level of river.    ADVANTAGE - The power supply device is used to charge and to supply electric power to the electric equipment using electric-power-generated by solar cell at the lithium ion battery. The consumption energy saving effect of the electric equipment is attained by adoption of the air system by the cooling fan, without using temperature control unit such as Peltier device. The air-blower control unit is used to control air flow of the air blower, to carry out electric power generation in the solar cell, with respect to application of atmospheric-temperature conditions. The power supply device is configured to ensure safety to the environment, even if the power supply device is installed in outdoor environment. The occurrence of the noise at time of driving the air blower can be prevented. The upper limit temperature of the storage battery is set as low or high value, after performing charging operation to storage battery, so that the power-saving operation is effectively performed, deterioration of the storage battery performance is prevented, and occurrence of danger by usage of the power supply device is prevented.    DESCRIPTION OF DRAWING(S) - The drawing shows the block diagram of the structure of the power supply device. (Drawing includes non-English language text)    Solar cell (11)    Storage battery (16)    Power supply device (30)    Charge-and-discharge control unit (31)    Detection unit (32)    Air blower (33)    Air-blower control unit (34)