Battery Diagnosing Apparatus and Method

An apparatus and method for diagnosing a battery bank having a failure in a connection state, including a state measuring unit configured to measure a state of each battery bank of a battery pack during a charging process and a discharging process of the battery pack; and a control unit configured to extract at least one battery bank by comparing states of the battery banks measured during the charging process of the battery pack with each other, extract at least one battery bank by comparing states of the battery banks measured during the discharging process of the battery pack with each other, and distinguish a battery bank having a failure in a connection state based on whether the battery banks respectively extracted during the charging process and the discharging process are identical to each other.