voltage detection circuitry to detect a terminal voltage of the storage battery;

time-series data acquisition circuitry to acquire time-series data on the terminal voltage in a stopped state of the storage battery;

model provision circuitry to provide a storage battery model that includes an OCV term for expressing OCV of the storage battery, and an interparticle diffusion term which is based on a fundamental solution of a one-dimensional diffusion equation expressing ion diffusion among particles forming an electrode of the storage battery; and

model parameter estimation circuitry to estimate a model parameter of the storage battery model based on the time-series data on the terminal voltage acquired by the time-series data acquisition circuitry and on the storage battery model provided by the model provision circuitry.