Charging control unit

A solar ECU (31) constituting a charging controller (30) activates by receiving all electric power generated directly from an onboard solar cell (21) without the use of a delay element for delaying a rise in starting voltage. The solar ECU (31) preferentially supplies the electric power generated by the onboard solar cell (21) to a sub-battery (19) and controls charging. Specifically, the solar ECU (31) preferentially supplies surplus electric power remaining after the solar ECU (31) has consumed power from the electric power generated by the onboard solar cell (21) to the sub-battery (19) when the charged amount of the sub-battery (19) is equal to or less than a prescribed charged amount. The solar ECU (31) thereby quickly activates and controls charging, whereby the electric power generated by the onboard solar cell (21), i.e., renewable energy, can be efficiently utilized without being needlessly wasted.