A condition estimation device (20, 62) for estimating condition of an electric storage device, the condition estimation device (20, 62) comprising: a voltage detector configured to detect a voltage of the electric storage device; a controller configured to perform: a distinctive point detection process to detect a distinctive point based on the voltage detected by the voltage detector, the distinctive point being a point at which a variation in voltage per unit remaining capacity or per unit time of the electric storage device during charge or discharge is a local maximum value; and an estimation process to estimate the condition of the electric storage device based on the distinctive point detected in the distinctive point detection process; characterized in that the controller is further configured to: perform a period measurement process to measure a period from when the distinctive point detected in the distinctive point detection process appears until when a voltage of the electric storage device reaches a set voltage; and perform the estimation process to estimate, as the condition of the electric storage device, a battery capacity or a remaining capacity of the electric storage device based on the period measured in the period measurement process. a voltage detector configured to detect a voltage of the electric storage device; a controller configured to perform: a distinctive point detection process to detect a distinctive point based on the voltage detected by the voltage detector, the distinctive point being a point at which a variation in voltage per unit remaining capacity or per unit time of the electric storage device during charge or discharge is a local maximum value; and an estimation process to estimate the condition of the electric storage device based on the distinctive point detected in the distinctive point detection process; a distinctive point detection process to detect a distinctive point based on the voltage detected by the voltage detector, the distinctive point being a point at which a variation in voltage per unit remaining capacity or per unit time of the electric storage device during charge or discharge is a local maximum value; and an estimation process to estimate the condition of the electric storage device based on the distinctive point detected in the distinctive point detection process; characterized in that the controller is further configured to: perform a period measurement process to measure a period from when the distinctive point detected in the distinctive point detection process appears until when a voltage of the electric storage device reaches a set voltage; and perform the estimation process to estimate, as the condition of the electric storage device, a battery capacity or a remaining capacity of the electric storage device based on the period measured in the period measurement process. perform a period measurement process to measure a period from when the distinctive point detected in the distinctive point detection process appears until when a voltage of the electric storage device reaches a set voltage; and perform the estimation process to estimate, as the condition of the electric storage device, a battery capacity or a remaining capacity of the electric storage device based on the period measured in the period measurement process.