Abstract: An output control method for a secondary battery includes: calculating a variation indication amount that correlates with a magnitude of variation between charge and discharge characteristics of the plurality of cells, based on a charge and discharge characteristic indication amount that changes according to change in the charge and discharge characteristic; determining that the variation occurs when the variation indication amount is equal to or larger than a predetermined determination reference value; and setting the available output power based on a determination result that the variation occurs. In the available output power setting step, when the variation does not occur, a basic available output power determined based on the charge and discharge characteristic indication amount is set as the available output power. When the variation occurs, a corrected available output power having a value lower than that of the basic available output power is set as the available output power.