A power supply control circuit connectable at an input (SLRA; SLRC) to a power supply apparatus and at an output (TVDD, TVTKP; TVSS) to a storage device (12, 22) that stores power supplied by the power supply apparatus; the power supply control circuit comprising: a) a charging current detector, inserted in a first connection line from a first input terminal (SLRA) of said input to a first output terminal (TVTKP) of said output, for detecting the charging current (I C) flowing from the power supply apparatus to the storage device in said first connection line, b) a blocking unit, inserted in a second connection line from a second output terminal (TVSS) of said output to a second input terminal (SLRC) of said output, for cutting off the backflow current (I R) that flows from the storage device to the power supply apparatus in said second connection line, on the basis of an inputted blocking control signal, and c) a backflow monitoring unit for monitoring said charging current detector by sampling for the presence of the charging current (I C) until the charging current(I C) is detected, constantly monitoring said charging current detector for the presence of the charging current (I C) after the charging current (I C) has been detected, and outputting a blocking control signal (S H) for cutting off the backflow current (I R) when the charging current (I C) is detected to not flow; and d) said backflow monitoring unit having a comparator being configured to compare voltage on both ends of the charging current detector, said comparator operating in response to a sampling timing signal; e) said backflow monitoring unit being further configured to monitor the presence of the charging current by the comparator comparing the voltage on both ends of said charging current detector in response to said sampling timing signal, until the charging current is detected, and f) said backflow monitoring unit being further configured to monitor constantly the presence of the charging current by the comparator constantly comparing the voltage on both ends of said current detector, after the charging current has been detected. a) a charging current detector, inserted in a first connection line from a first input terminal (SLRA) of said input to a first output terminal (TVTKP) of said output, for detecting the charging current (I C) flowing from the power supply apparatus to the storage device in said first connection line, b) a blocking unit, inserted in a second connection line from a second output terminal (TVSS) of said output to a second input terminal (SLRC) of said output, for cutting off the backflow current (I R) that flows from the storage device to the power supply apparatus in said second connection line, on the basis of an inputted blocking control signal, and c) a backflow monitoring unit for monitoring said charging current detector by sampling for the presence of the charging current (I C) until the charging current(I C) is detected, constantly monitoring said charging current detector for the presence of the charging current (I C) after the charging current (I C) has been detected, and outputting a blocking control signal (S H) for cutting off the backflow current (I R) when the charging current (I C) is detected to not flow; and d) said backflow monitoring unit having a comparator being configured to compare voltage on both ends of the charging current detector, said comparator operating in response to a sampling timing signal; e) said backflow monitoring unit being further configured to monitor the presence of the charging current by the comparator comparing the voltage on both ends of said charging current detector in response to said sampling timing signal, until the charging current is detected, and f) said backflow monitoring unit being further configured to monitor constantly the presence of the charging current by the comparator constantly comparing the voltage on both ends of said current detector, after the charging current has been detected.