A battery pack (40, 140, 240) comprising: a battery comprising at least one rechargeable battery (B1-Bn), the battery comprising a positive electrode and a negative electrode; a control unit configured to monitor a state of the battery and to control at least one of charge and discharge of the battery; a pair of external terminals (44A, 44B, 46D) configured for an electrical connection of an external device (10, 80), the pair of external terminals (44A, 44B, 46D) comprising a first external terminal and a second external terminal (44A, 46D); a first current cut-off unit provided in a power supply path (L2A, L2B) that is formed by connecting the battery and the pair of external terminals (44A, 44B, 46D) and through which flows at least one of a charge current and a discharge current, the first current cut-off unit being provided in a path (L2B) extending from the negative electrode of the battery to the first external terminal and being configured to be turned to one of an energized state and a cut-off state based on a command from the control unit, to thereby turn the power supply path (L2A, L2B) to one of an energized state and a cut-off state; a second current cut-off unit (72, 172) that is connected in series to the first current cut-off unit in the power supply path (L2A, L2B), the second current cut-off unit (72, 172) being provided in a path (L2A) extending from the positive electrode of the battery to the second external terminal (44A, 46D) and being configured to be turned to one of an energized state and a cut-off state based on a command from the control unit, to thereby turn the power supply path (L2A, L2B) to one of an energized state and a cut-off state; and a state determination circuit (76, 276) connecting a first path (L2Ba) extending from the first current cut-off unit to the first external terminal and a second path (L2Aa) extending from the second current cut-off unit to the second external terminal, wherein the control unit is configured to determine whether the first current cut-off unit and the second current cut-off unit (72, 172) are normal or abnormal based on a potential (Vch) in the state determination circuit (76, 276), the potential (Vch) varying according to a potential in the first path (L2Ba) or the second path (L2Aa), when neither charge nor discharge of the battery is performed, and configured to turn the first current cut-off unit and the second current cut-off unit (72, 172) to an energized state when the first current cut-off unit and the second current cut-off unit (72, 172) are both normal, and to turn at least one of the first current cut-off unit and the second current cut-off unit (72, 172) to a cut-off state when at least one of the first current cut-off unit and the second current cut-off unit (72, 172) is abnormal. a battery comprising at least one rechargeable battery (B1-Bn), the battery comprising a positive electrode and a negative electrode; a control unit configured to monitor a state of the battery and to control at least one of charge and discharge of the battery; a pair of external terminals (44A, 44B, 46D) configured for an electrical connection of an external device (10, 80), the pair of external terminals (44A, 44B, 46D) comprising a first external terminal and a second external terminal (44A, 46D); a first current cut-off unit provided in a power supply path (L2A, L2B) that is formed by connecting the battery and the pair of external terminals (44A, 44B, 46D) and through which flows at least one of a charge current and a discharge current, the first current cut-off unit being provided in a path (L2B) extending from the negative electrode of the battery to the first external terminal and being configured to be turned to one of an energized state and a cut-off state based on a command from the control unit, to thereby turn the power supply path (L2A, L2B) to one of an energized state and a cut-off state; a second current cut-off unit (72, 172) that is connected in series to the first current cut-off unit in the power supply path (L2A, L2B), the second current cut-off unit (72, 172) being provided in a path (L2A) extending from the positive electrode of the battery to the second external terminal (44A, 46D) and being configured to be turned to one of an energized state and a cut-off state based on a command from the control unit, to thereby turn the power supply path (L2A, L2B) to one of an energized state and a cut-off state; and a state determination circuit (76, 276) connecting a first path (L2Ba) extending from the first current cut-off unit to the first external terminal and a second path (L2Aa) extending from the second current cut-off unit to the second external terminal, wherein the control unit is configured to determine whether the first current cut-off unit and the second current cut-off unit (72, 172) are normal or abnormal based on a potential (Vch) in the state determination circuit (76, 276), the potential (Vch) varying according to a potential in the first path (L2Ba) or the second path (L2Aa), when neither charge nor discharge of the battery is performed, and configured to turn the first current cut-off unit and the second current cut-off unit (72, 172) to an energized state when the first current cut-off unit and the second current cut-off unit (72, 172) are both normal, and to turn at least one of the first current cut-off unit and the second current cut-off unit (72, 172) to a cut-off state when at least one of the first current cut-off unit and the second current cut-off unit (72, 172) is abnormal.