A battery management system, comprising: a plurality of diodes (121, 122, 123, 124, 125) which are configured to be connected in parallel to a plurality of battery cells (111, 112, 113, 114, 115), the plurality of battery cells (111, 112, 113, 114, 115), being connected in series; a switch unit which includes a plurality of switches (131, 132, 133, 134, 135) respectively configured to be connected to the plurality of battery cells (111, 112, 113, 114, 115); a control unit which is configured to detect voltages of the plurality of battery cells (111, 112, 113, 114, 115) and is configured to perform cell balancing; and a plurality of sensing lines (141, 142, 143, 144, 145) which are configured to connect the plurality of battery cells (111, 112, 113, 114, 115) and the control unit, wherein the control unit is further configured to: measure a first upper voltage difference between each battery cell (111, 112, 113, 114, 115) and an adjacent upper battery cell in a state in which the switches (131, 132, 133, 134, 135) are turned off, measure a second upper voltage difference between each battery cell (111, 112, 113, 114, 115) and the adjacent upper battery cell after turning on the switches (131, 132, 133, 134, 135) for a predetermined time, when the second upper voltage difference is greater than the first upper voltage difference, determine that a sensing line of a corresponding battery cell is a disconnected sensing line, characterised in that the control unit is further configured to: measure a first lower voltage difference between each battery cell (111, 112, 113, 114, 115) and an adjacent lower battery cell in a state in which the switches (131, 132, 133, 134, 135) are turned off, measure a second lower voltage difference between each battery cell (111, 112, 113, 114, 115) and the adjacent lower battery cell after turning on the switches (131, 132, 133, 134, 135) for a predetermined time, and when the second lower voltage difference is smaller than the first lower voltage difference, determine that the sensing line of the corresponding battery cell is disconnected. a plurality of diodes (121, 122, 123, 124, 125) which are configured to be connected in parallel to a plurality of battery cells (111, 112, 113, 114, 115), the plurality of battery cells (111, 112, 113, 114, 115), being connected in series; a switch unit which includes a plurality of switches (131, 132, 133, 134, 135) respectively configured to be connected to the plurality of battery cells (111, 112, 113, 114, 115); a control unit which is configured to detect voltages of the plurality of battery cells (111, 112, 113, 114, 115) and is configured to perform cell balancing; and a plurality of sensing lines (141, 142, 143, 144, 145) which are configured to connect the plurality of battery cells (111, 112, 113, 114, 115) and the control unit, wherein the control unit is further configured to: measure a first upper voltage difference between each battery cell (111, 112, 113, 114, 115) and an adjacent upper battery cell in a state in which the switches (131, 132, 133, 134, 135) are turned off, measure a second upper voltage difference between each battery cell (111, 112, 113, 114, 115) and the adjacent upper battery cell after turning on the switches (131, 132, 133, 134, 135) for a predetermined time, when the second upper voltage difference is greater than the first upper voltage difference, determine that a sensing line of a corresponding battery cell is a disconnected sensing line, measure a first upper voltage difference between each battery cell (111, 112, 113, 114, 115) and an adjacent upper battery cell in a state in which the switches (131, 132, 133, 134, 135) are turned off, measure a second upper voltage difference between each battery cell (111, 112, 113, 114, 115) and the adjacent upper battery cell after turning on the switches (131, 132, 133, 134, 135) for a predetermined time, when the second upper voltage difference is greater than the first upper voltage difference, determine that a sensing line of a corresponding battery cell is a disconnected sensing line, measure a first lower voltage difference between each battery cell (111, 112, 113, 114, 115) and an adjacent lower battery cell in a state in which the switches (131, 132, 133, 134, 135) are turned off, measure a second lower voltage difference between each battery cell (111, 112, 113, 114, 115) and the adjacent lower battery cell after turning on the switches (131, 132, 133, 134, 135) for a predetermined time, and when the second lower voltage difference is smaller than the first lower voltage difference, determine that the sensing line of the corresponding battery cell is disconnected.