[Object] To accurately measure the internal temperature of an electrical storage device without the need for complex computational processing.
[Solution] An electrical storage device temperature-measuring method includes: measuring the real part of the internal impedance of an electrical storage device (101) by using an alternating-current signal having a frequency at which the internal impedance or the real part of the internal impedance of the electrical storage device (101) does not change according to the remaining capacity (SOC: state of charge) of the electrical storage device (101); and calculating the internal temperature of the electrical storage device (101) from the measured value of the real part of the internal impedance.