In a battery model identification method of the present invention, an M-sequence input electric current production part inputs M-sequence signals with different frequency components as an electric current input into the battery. In this occasion, terminal voltage of the battery is measured by a voltage sensor, and a parameter estimation part executes system identification based on the measured result to calculate frequency characteristics of the battery. Resistance components and capacitance components as parameters of a battery model are identified based on the calculated frequency characteristics.