Provided are: an electric storage device having improved reliability in charging a storage battery; and a charging method. This electric storage device is provided with: an SOC calculation section which calculates a charge rate when a battery voltage reached a predetermined value, in the cases where the battery voltage reached the predetermined value when a lithium ion storage battery is being charged; a voltage difference calculation section, which calculates a battery voltage difference corresponding to a difference between the charge rate and a charge rate at which lithium is deposited; a charge complete voltage calculation means, which calculates a charge complete voltage by adding the voltage difference to the battery voltage obtained when the battery voltage reached the predetermined value; and a charge control means, which completes the charging of the lithium ion storage battery in the cases where the battery voltage reached the charge complete voltage.