A battery controller that performs current limitation in consideration of limitation on other components than a battery main body and the state of health of a battery is provided. A battery controller limits a battery current using allowable average current information describing current average values respectively allowed for a plurality of time windows. When the battery is deteriorated, an allowable average current obtained by subtraction in response to the state of health is used. Further, when the battery current exceeds an upper limit value stored in advance, the battery current is controlled with the upper limit reduced by the excessive amount.