A charging control device configured to use an in-vehicle solar cell for installation in a vehicle, the vehicle comprising: a motor generator (13, 14) configured to generate a driving force and to generate regenerative electric power; a main battery electrically connected to the motor generator (13, 14), the main battery being configured to supply electric power to the motor generator (13, 14) and to store the regenerative electric power; and a sub-battery configured to supply electric power to various accessory devices mounted on the vehicle, the vehicle being capable of traveling using at least the driving force generated by the motor generator (13, 14), the charging control device characterized by comprising: an electric power supply unit comprising an in-vehicle solar cell, which is configured to supply electric power generated by the in-vehicle solar cell to at least one of a main battery and a sub-battery and a low-voltage battery configured to temporarily store the electric power generated by the in-vehicle solar cell; and a charging control unit configured to control charging of at least one of the main battery and the sub-battery using the electric power generated by the in-vehicle solar cell and supplied from the electric power supply unit, the charging control unit being configured to, when the vehicle in which the charging control device is installed is traveling, prevent the electric power generated by the in-vehicle solar cell from being supplied from the electric power supply unit to the main battery, and the charging control unit being configured to permit, when the vehicle in which the charging control device is installed, is not traveling, the electric power generated by the in-vehicle solar cell and temporarily stored in the low-voltage battery, to be supplied from the low-voltage battery to the main battery, wherein the charging control unit is configured to at least, when the vehicle is traveling, supply the electric power generated by the in-vehicle solar cell and temporarily stored in the low-voltage battery to the sub-battery, wherein the charging control unit is configured to permit, when the vehicle is not travelling and an amount of the electric power generated by the in-vehicle solar cell is more than a predetermined amount of electric power set in advance, the electric power generated by the in-vehicle solar cell to be supplied from the electric power supply unit to the main battery, and wherein the predetermined amount of electric power is set to an amount of electric power consumed when an electronic component required for the charging of the main battery is operating as a result of the charging control of the main battery. a motor generator (13, 14) configured to generate a driving force and to generate regenerative electric power; a main battery electrically connected to the motor generator (13, 14), the main battery being configured to supply electric power to the motor generator (13, 14) and to store the regenerative electric power; and a sub-battery configured to supply electric power to various accessory devices mounted on the vehicle, the vehicle being capable of traveling using at least the driving force generated by the motor generator (13, 14), an electric power supply unit comprising an in-vehicle solar cell, which is configured to supply electric power generated by the in-vehicle solar cell to at least one of a main battery and a sub-battery and a low-voltage battery configured to temporarily store the electric power generated by the in-vehicle solar cell; and a charging control unit configured to control charging of at least one of the main battery and the sub-battery using the electric power generated by the in-vehicle solar cell and supplied from the electric power supply unit, the charging control unit being configured to, when the vehicle in which the charging control device is installed is traveling, prevent the electric power generated by the in-vehicle solar cell from being supplied from the electric power supply unit to the main battery, and the charging control unit being configured to permit, when the vehicle in which the charging control device is installed, is not traveling, the electric power generated by the in-vehicle solar cell and temporarily stored in the low-voltage battery, to be supplied from the low-voltage battery to the main battery, wherein the charging control unit is configured to at least, when the vehicle is traveling, supply the electric power generated by the in-vehicle solar cell and temporarily stored in the low-voltage battery to the sub-battery, wherein the charging control unit is configured to permit, when the vehicle is not travelling and an amount of the electric power generated by the in-vehicle solar cell is more than a predetermined amount of electric power set in advance, the electric power generated by the in-vehicle solar cell to be supplied from the electric power supply unit to the main battery, and wherein the predetermined amount of electric power is set to an amount of electric power consumed when an electronic component required for the charging of the main battery is operating as a result of the charging control of the main battery.