A switch diagnosing apparatus, which diagnoses switches (11, 12, 21, 22, 31, 32) provided to a plurality of battery modules (10, 20, 30) respectively having at least one secondary battery and connected to each other in parallel, the switch diagnosing apparatus comprising: a plurality of positive electrode module switches (11, 21, 31) respectively provided to a positive electrode charging and discharging path directly connected to positive electrode terminals of the plurality of battery modules (10, 20, 30) to open or close the positive electrode charging and discharging path; a plurality of negative electrode module switches (12, 22, 32) respectively provided to a negative electrode charging and discharging path directly connected to negative electrode terminals of the plurality of battery modules (10, 20, 30) to open or close the negative electrode charging and discharging path; a plurality of positive electrode diagnosis terminals (110, 120, 130) provided to a positive electrode charging and discharging path between each positive electrode module switch (11, 21, 31) and a positive electrode terminal of a battery pack; a plurality of negative electrode diagnosis terminals (210, 220, 230) provided to a negative electrode charging and discharging path between each negative electrode module switch (12, 22, 32) and a negative electrode terminal of the battery pack; a voltage measuring unit configured to measure voltages of the plurality of positive electrode diagnosis terminals (110, 120, 130) and the plurality of negative electrode diagnosis terminals (210, 220, 230); a processor configured to receive the voltages of the plurality of positive electrode diagnosis terminals (110, 120, 130) and the plurality of negative electrode diagnosis terminals (210, 220, 230) from the voltage measuring unit; and characterized in that the processor is configured to: select a diagnosis target battery module among the plurality of battery modules (10, 20, 30), diagnose that the positive electrode module switch and the negative electrode module switch of the diagnosis target battery module are in the stalled state when a voltage difference between the positive electrode diagnosis terminal and the negative electrode diagnosis terminal provided to a battery module other than the diagnosis target battery module is equal to or greater than a predetermined threshold value. a plurality of positive electrode module switches (11, 21, 31) respectively provided to a positive electrode charging and discharging path directly connected to positive electrode terminals of the plurality of battery modules (10, 20, 30) to open or close the positive electrode charging and discharging path; a plurality of negative electrode module switches (12, 22, 32) respectively provided to a negative electrode charging and discharging path directly connected to negative electrode terminals of the plurality of battery modules (10, 20, 30) to open or close the negative electrode charging and discharging path; a plurality of positive electrode diagnosis terminals (110, 120, 130) provided to a positive electrode charging and discharging path between each positive electrode module switch (11, 21, 31) and a positive electrode terminal of a battery pack; a plurality of negative electrode diagnosis terminals (210, 220, 230) provided to a negative electrode charging and discharging path between each negative electrode module switch (12, 22, 32) and a negative electrode terminal of the battery pack; a voltage measuring unit configured to measure voltages of the plurality of positive electrode diagnosis terminals (110, 120, 130) and the plurality of negative electrode diagnosis terminals (210, 220, 230); a processor configured to receive the voltages of the plurality of positive electrode diagnosis terminals (110, 120, 130) and the plurality of negative electrode diagnosis terminals (210, 220, 230) from the voltage measuring unit; and characterized in that the processor is configured to: select a diagnosis target battery module among the plurality of battery modules (10, 20, 30), diagnose that the positive electrode module switch and the negative electrode module switch of the diagnosis target battery module are in the stalled state when a voltage difference between the positive electrode diagnosis terminal and the negative electrode diagnosis terminal provided to a battery module other than the diagnosis target battery module is equal to or greater than a predetermined threshold value. select a diagnosis target battery module among the plurality of battery modules (10, 20, 30), diagnose that the positive electrode module switch and the negative electrode module switch of the diagnosis target battery module are in the stalled state when a voltage difference between the positive electrode diagnosis terminal and the negative electrode diagnosis terminal provided to a battery module other than the diagnosis target battery module is equal to or greater than a predetermined threshold value.