The invention provides a multi-series connection type battery cell pack, characterized by comprising a plurality of series-connected battery cells 1, a charge/discharge control switch 2 for performing charge/discharge control, a plurality of protective circuits 3-1 and 3-2 for dividing the plurality of battery cells 1 into a plurality of blocks to detect at least the voltage of each battery cell, a computing circuit 5 for performing computation of pack detection signals and a level conversion circuit 4 for unifying voltages references of the detection signals between the plurality of protective circuits 3-1 and 3-2 and the computing circuit 5, wherein the plurality of protective circuits 3-1 and 3-2 are joined in parallel with the battery cells 1 in a multistage fashion. It is thus possible to unify the voltage references while computation and communication are executed irrespective of control. It is then possible to manage the battery cell pack in a unified manner using a microcomputer or the like and, hence, to determine management specific to batteries and operational criteria specific to battery products at users' disposal. It is also possible to make a switching between a mode wherein current consumption in the pack minimizes and a normal operation mode and, hence, switch the pack over to the minimum current consumption mode when it is not in use, thereby reducing the failure rate during long-term storage.