A charging control system for controlling a charging power or a charging current for charging a battery, comprising: a voltage detector configured to detect a voltage of the battery; an upper-limit voltage calculating section configured to calculate an upper-limit voltage of the battery; an internal resistance line calculating section configured to calculate an internal resistance line indicating a relation between a value of a charging current and a value of a voltage of the battery, which voltage occurs when the charging current has flown into the battery; a maximum inputtable value calculating section configured to calculate, based on the detected voltage of the battery, the calculated upper-limit voltage of the battery, and the calculated internal resistance line, a maximum inputtable value corresponding to a maximum inputtable power or current that can be inputted into the battery; characterized by a target point calculating section configured to calculate a point located between a maximum inputtable value point, existing on the internal resistance line and corresponding to the maximum inputtable value, and a currently-inputted value point, existing on the internal resistance line and corresponding to a charging power/current currently inputted to the battery, as a target point corresponding to a target charging power/current point; an input value setting section configured to set, based on the calculated target point, the charging power or the charging current for charging the battery; and a charging-control section configured to repeatedly execute a charging-control cycle, which includes the calculation of the internal resistance line, the calculation of the target point as a point located between the maximum inputtable value and the currently-inputted value, and the setting of the charging power or the charging current based on the calculated target point, every predetermined time intervals. a voltage detector configured to detect a voltage of the battery; an upper-limit voltage calculating section configured to calculate an upper-limit voltage of the battery; an internal resistance line calculating section configured to calculate an internal resistance line indicating a relation between a value of a charging current and a value of a voltage of the battery, which voltage occurs when the charging current has flown into the battery; a maximum inputtable value calculating section configured to calculate, based on the detected voltage of the battery, the calculated upper-limit voltage of the battery, and the calculated internal resistance line, a maximum inputtable value corresponding to a maximum inputtable power or current that can be inputted into the battery; characterized by a target point calculating section configured to calculate a point located between a maximum inputtable value point, existing on the internal resistance line and corresponding to the maximum inputtable value, and a currently-inputted value point, existing on the internal resistance line and corresponding to a charging power/current currently inputted to the battery, as a target point corresponding to a target charging power/current point; an input value setting section configured to set, based on the calculated target point, the charging power or the charging current for charging the battery; and a charging-control section configured to repeatedly execute a charging-control cycle, which includes the calculation of the internal resistance line, the calculation of the target point as a point located between the maximum inputtable value and the currently-inputted value, and the setting of the charging power or the charging current based on the calculated target point, every predetermined time intervals.