The present invention contributes to improving reliability by accurately perceiving the capacity of a lead battery as accurately as possible and more suitably estimating the degree of deterioration of a lead battery that is being used. The present invention comprises: an actual measured capacity calculation unit (135) which measures the capacity of a lead battery (B); a recording unit (12) which records an actual measured capacity of the lead battery (B) that is actually measured by the actual measured capacity calculation unit (135) and operation history information about the lead battery (B) when the actual measured capacity is measured; and a capacity deterioration estimation re-optimization unit (136) which estimates the deterioration in capacity of the lead battery (B) on the basis of the actual measured capacity, wherein the actual measured capacity calculation unit (135) measures the actual measured capacity on the basis of an electric quantity during discharge of the lead battery (B) when the lead battery (B) to be measured has been charged and is then discharged, and the capacity deterioration estimation re-optimization unit (136) estimates the deterioration in capacity of the lead battery (B) on the basis of all the actual measured capacity that has been measured until now by the actual measured capacity calculation unit and includes a latest actual measured capacity obtained with the latest measurement.