A device for estimating parameters of battery capable of improving, by using simple calculations, estimation accuracy of a parameter and the like of a battery equivalent circuit model will be provided.The device for estimating parameters of battery for estimating the parameter of a battery (1) includes: a battery equivalent circuit model (4A) including resistance and a capacitor as the parameter; a logarithmic conversion parameter value estimation unit (4B) for sequentially estimating, by using a logarithmic conversion parameter value serving as a state variable obtained by carrying out logarithmic conversion on the parameter, the logarithmic conversion parameter value with a Kalman filter (41) from a state equation and an output equation, based on a charging/discharging current and a terminal voltage those being detected; and an inverse logarithmic conversion unit (4C) for obtaining, from the logarithmic conversion parameter value, an estimated parameter value serving as an antilogarithm corresponding to the logarithmic conversion parameter value.