The battery monitoring chips each include a battery monitoring function section that is provided so as to correspond to a respective battery cell group and to monitor a state of each battery cell contained in the corresponding battery cell group, and a regulator that generates a drive voltage to supply to a configuration circuit of the battery monitoring function section based on power supplied from the battery. The battery monitoring chips are connected together in series to give a communication path, with an input end of the regulator electrically connected to an output end of another regulator. A microcomputer is connected to a battery monitoring chip, and is driven by a drive voltage generated by the regulator of the battery monitoring chip accompanying power consumption by each of the battery cells.