Electrical storage device temperature measuring method

Object of the present invention is to accurately measure the internal temperature of the storage device without performing complicated arithmetic processing. To this end, the present invention is characterized by using a power storage device (101) or internal impedance without actually portion (101) of the remaining capacity of the electric storage device according to (SOC: State OfCharge) varying the frequency of the AC signal to measure the accumulation occurs the real part of the internal impedance of the power supply device (101), and calculates the internal temperature of the power storage device (101) based on the measured value of the real part of the internal impedance.