A method of estimating a battery state includes acquiring one or more parameters for estimating a present state of the battery based on a previous state of the battery; acquiring a present usage environment of the battery; and estimating the present state by applying any one or any combination of any two or more of the previous state, the present usage environment, and the acquired one or more parameters to an electrochemical model that is expressed by simplified parameters simplified by either one or both of parameter grouping and partial non-dimensionalising of an electrochemical reaction governing equation of the battery.