PURPOSE: To provide a charge/discharge circuit for batteries for emergency wherein at least two nickel-cadmium cells are used, wherein the cells are com pletely charged or discharged to avoid the occurrence of memory effect, and wherein the full capacity of each battery is always available.

CONSTITUTION: The title charge/discharge circuit for batteries for emergency consists of a first switch 6 that switches the connection of a plurality of nickel- cadmium cells 51, 52 between to the load side and to the charge/discharge side; a second switch 7 that switches the connection of the cells 51, 52, connected to the charge/discharge side, between to a discharger 9 and to a charger 8; the discharger 9; the charger 8; a timer 12; a service interruption detection unit 10 that detects service interruption; a control unit 13 that controls the first and second switches 6, 7 and so on according to detection signals and the lapse of time on the timer; and a voltage detection unit 11 that detects load voltage. Thus the cells are alternately charged and discharged, and the fully charged cell is used if a service interruption occurs.