Provided is a cell capacity adjusting device for reducing fluctuations in state of charge (SOC) among cells of a battery pack 101, which is formed by connecting a plurality of cells 111-116 in series, during suspension of operation of electrically-powered equipment whose main power source is the battery pack 101. From among the plurality of cells 111-116, one or a plurality of cells having a voltage value equal to or higher than a cell capacity adjustment target voltage are selected. By the selected cells, an intermittent operation unit 105, which operates even during the suspension of operation of the electrically-powered equipment, is caused to perform an intermittent operation. Through repetition of the intermittent operation, voltage values of the selected cells are decreased. Thus, fluctuations in state of charge (SOC) among cells are reduced without unnecessarily discharging battery stored energy of the battery pack 101.