An apparatus, a method and a battery pack for detecting a fault of at least one of first and second electrical conductors connected to a positive terminal and a negative terminal of the battery, respectively. The apparatus includes a current sensor measuring a battery current, a voltage sensor measuring a voltage between the first electrical conductor and the second electrical conductor as a battery voltage, and a control unit. The control unit determines an idle voltage value indicating the battery voltage measured while charging and discharging of the battery is stopped. The control unit determines a diagnosis voltage value indicating the battery voltage measured while the battery is being charged or discharged. The control unit determines whether at least one of the first and second electrical conductors is faulty based on a difference between the idle voltage value and the diagnosis voltage value.