The present invention relates to a series charger with separate detection of batteries which includes a charging control device for converting the inputted AC power into DC power so as to charging four batteries in series connection. The charging control device further provides a reference voltage source to a control IC which is connected with a current detector for measuring the current value of the batteries. Each of the series-connected batteries is parallel-connected with a switch element. A one-way diode is interposed between the positive end of the batteries and each of the switch elements. Besides, the control IC provides -.DELTA.V to the positive terminal of the respective charging circuit of the batteries for detecting the end-point voltage thereof. When each of the batteries is fully charged, the respective switch element is switched in a close circuit so that the charging current continues to flow downward for further charging operation. Moreover, after all batteries are fully charged one after another, the current detector is used to regulate the charging current or the switch-on time of the switch elements is controlled for proceeding with supplementary charging procedure.