A remaining battery power calculation circuit includes: a detection unit configured to detect an output voltage of a battery; a data storage unit configured to store data in an associated manner with each of a plurality of current values for charge or discharge of the battery, the data indicating a relationship between the output voltage and a ratio of remaining power of the battery to a capacity of the battery in a case where the battery is charged or discharged with each of the plurality of current values; and a first calculation unit configured to calculate a charging/discharging current of the battery based on the data and the output voltage.