Apparatus and Method for Managing Battery

A battery management apparatus includes an SOC calculation unit to calculate an SOC of a battery module by using at least one of voltage, current, or temperature measured for the battery module in which a plurality of battery cells are connected in parallel, an SOH calculation unit to calculate an SOH of the battery module based on at least one of the SOC calculated by the SOC calculation unit and the voltage, current, or temperature of the battery module, and a diagnosis unit to calculate a change rate of an SOH using the SOH, and diagnose a state of the battery module using the calculated SOH change rate. The state of the battery module is any one of a normal state, a state including a degenerate battery cell, or a state including a current interrupt device (CID) open battery cell.