Abstract: A power supply apparatus 11 and a storage device 12 that stores power supplied by the power supply apparatus 11 interpose a power supply control circuit 10. The circuit has a charging current detector 13 to detect charging current IC flowing from the power supply apparatus 11 to the storage device 12; a blocking unit 15 to interrupt the backflow current IR that flows from the storage device to the power supply apparatus on the basis of an inputted blocking control signal SH; and a backflow monitoring unit 14 to monitor by sampling for the presence of the charging current IC until the charging current IC is detected, constantly to monitor for the presence of the charging current IC after the charging current IC has been detected, and to output a blocking control signal SH for cutting off the backflow current IR when the charging current IC is not flowing.