A battery state estimating apparatus is provided with; a voltage detector configured to detect a voltage between a positive electrode and a negative electrode of a battery; an impedance detector configured to detect an impedance of the battery; a first estimator configured to estimate a first temporary value of a charge amount of the battery; a second estimator configured to estimate a second temporary value of the charge amount of the battery; and a determinator configured (i) to determine that the first temporary value is the charge amount of the battery if the first temporary value or the second temporary value is out of a predetermined range, and (ii) to determine that the second temporary value, or a corrected value of the first temporary value is the charge amount of the battery if the first temporary value or the second temporary value is within the predetermined range.