A current control circuit for controlling a voltage to an external device from a photoelectric conversion module, the current control circuit comprising: a current control unit connectable between the energy harvesting unit and an external device; a first voltage control unit controlling the current control unit so that an input voltage to the current control unit becomes equal to or higher than a first voltage; and a second voltage control unit controlling the current control unit so that an output voltage from the current control unit becomes equal to or lower than a second voltage which is equal to or higher than the first voltage, wherein: the current control unit includes a transistor or an FET, the first voltage control unit further includes a first resistor, a second resistor, a third resistor and a diode, the first resistor being connected between the input to the current control unit and a first node, the second resistor being connected between the first node and ground, the third resistor being connected between the input to the current control unit and a second node, and the diode having its anode connected to the second node and its cathode connected to ground, the first voltage control unit and the second voltage control unit include a common differential amplifier (31, 42), having a first input connected to the first node, a second input connected to the second node, and an output connected to the current control unit, the second voltage control unit further includes a Zener diode, a fourth resistor and a FET, the Zener diode having an anode and a cathode, the cathode being connected to the output of the current control unit, the fourth resistor being connected between the anode of the Zener and ground, the FET having a gate, a drain and a source, the gate of the FET being connected to the anode of the Zener diode, the drain of the FET being connected to the first node, and the source of the FET being connected to ground. a current control unit connectable between the energy harvesting unit and an external device; a first voltage control unit controlling the current control unit so that an input voltage to the current control unit becomes equal to or higher than a first voltage; and a second voltage control unit controlling the current control unit so that an output voltage from the current control unit becomes equal to or lower than a second voltage which is equal to or higher than the first voltage, the current control unit includes a transistor or an FET, the first voltage control unit further includes a first resistor, a second resistor, a third resistor and a diode, the first resistor being connected between the input to the current control unit and a first node, the second resistor being connected between the first node and ground, the third resistor being connected between the input to the current control unit and a second node, and the diode having its anode connected to the second node and its cathode connected to ground, the first resistor being connected between the input to the current control unit and a first node, the second resistor being connected between the first node and ground, the third resistor being connected between the input to the current control unit and a second node, and the diode having its anode connected to the second node and its cathode connected to ground, the first voltage control unit and the second voltage control unit include a common differential amplifier (31, 42), having a first input connected to the first node, a second input connected to the second node, and an output connected to the current control unit, the second voltage control unit further includes a Zener diode, a fourth resistor and a FET, the Zener diode having an anode and a cathode, the cathode being connected to the output of the current control unit, the fourth resistor being connected between the anode of the Zener and ground, the FET having a gate, a drain and a source, the gate of the FET being connected to the anode of the Zener diode, the drain of the FET being connected to the first node, and the source of the FET being connected to ground. the Zener diode having an anode and a cathode, the cathode being connected to the output of the current control unit, the fourth resistor being connected between the anode of the Zener and ground, the FET having a gate, a drain and a source, the gate of the FET being connected to the anode of the Zener diode, the drain of the FET being connected to the first node, and the source of the FET being connected to ground.