A charge state detection circuit, which detects a
state of charge of a battery block in which are parallel-connected a plurality of series circuits of a secondary battery and a cutoff element which assumes a cutoff state of
cutting off the charge /
discharge path of the secondary battery and a conducting state different from the cutoff state, the charge state detection circuit comprising: an effective battery number detection portion which detects, as the number of effective batteries, the number of cutoff elements in the conducting state from among the plurality of cutoff elements included in the battery block; a capacity information generation portion which, based on the number of effective batteries, generates capacity information related to actual full charge capacity, which is the actual full charge capacity of the battery block; a
total current detection portion, which detects as a
total current value a current flowing in the entire battery block; an
electricity quantity calculation portion, which calculates, as a stored
electricity quantity, an
electricity quantity stored in the battery block, by integrating the
total current value; and a charge state detection portion, which, based on the capacity information and the stored electricity quantity, detects a
state of charge, which is a ratio of the stored electricity quantity to the actual full charge capacity.