An apparatus and method for battery parameter estimation estimate the parameters of a battery equivalent circuit model while reducing the computation load. The apparatus includes a charge/discharge current detector (3) that detects a charge/discharge current value of a battery (1); a terminal voltage detector (2) that detects a terminal voltage value of the battery (1); and an estimator (4) that estimates, based on the charge/discharge current value and the terminal voltage value, parameters in a battery equivalent circuit model (41) that approximates the Warburg impedance of the battery (1).