Battery soundness estimation device and soundness estimation method

A battery soundness estimation device and soundness estimation method which improve the accuracy of battery soundness estimation are provided. This battery soundness estimation device is provided with a charge/discharge current detection unit (1) which detects the charge/discharge current value, a terminal voltage detection unit (2) which detects the terminal voltage, a first charging rate estimation unit (4) which estimates the first charging rate by integrating the charge/discharge current rate, a second charging rate estimation unit (5) which estimates the second charging rate on the basis of the relation between the open circuit voltage and the charging rate, a first soundness estimation unit (6) which estimates a first soundness on the basis of the first and second charging rates, a second soundness estimation unit (7) which estimates a second soundness on the basis of the relation between the battery internal resistance and the soundness, and a first correction value calculation unit (9) which, on the basis of the difference between the first soundness and the second soundness, calculates a first correction value for correcting the first charging rate. The first charging rate estimation unit (4) corrects the first charging rate using the first correction value.