A battery module, comprising: a pair of battery cells respectively having electrode leads and stacked to face each other; a connector configured to connect the electrode leads of the pair of battery cells; and a connector breaking device disposed in a space formed between terrace portions of the pair of battery cells, the connector breaking device is configured to be operated with a pressure applied due to swelling of the battery cells so as to cut off an electric connection between the connector and the electrode leads, wherein the electrode leads respectively provided at the pair of battery cells are fixed to the connector breaking device, wherein the connector breaking device includes: a push bar configured to move upwards inside a cartridge with a pressure applied due to swelling of the battery cell; a first elastic member configured to maintain an elastically compressed state in a direction opposite to the electrode lead and be restored when the push bar moves upwards; and a breaking unit configured to move toward the connector through an opening formed at a top end of the cartridge due to a restoring force of the first elastic member so as to cut off an electric connection between the connector and the electrode lead, wherein the cartridge is configured to accommodate the push bar, the first elastic member and the breaking unit, wherein the connector breaking device further includes a stopper configured to fix the breaking unit so that the first elastic member maintains a compressed state, the stopper releasing a fixed state of the breaking unit when the push bar is compressed due to swelling so that the breaking unit moves toward the connector due to the restoring force of the first elastic member, wherein the cartridge includes a guide rib formed to protrude from an inner surface thereof and inclined at a predetermined angle with respect to a horizontal line wherein the push bar includes a push rib extending upwards toward the guide rib and having one end located between the guide rib and the stopper, wherein when the push bar is compressed due to the swelling, the push rib changes a moving direction by the guide rib so that one end of the push rib applies a pressure to one end of the stopper, wherein the stopper moves with a pressure applied by the push rib to release the fixed state of the breaking unit. a pair of battery cells respectively having electrode leads and stacked to face each other; a connector configured to connect the electrode leads of the pair of battery cells; and a connector breaking device disposed in a space formed between terrace portions of the pair of battery cells, the connector breaking device is configured to be operated with a pressure applied due to swelling of the battery cells so as to cut off an electric connection between the connector and the electrode leads, wherein the electrode leads respectively provided at the pair of battery cells are fixed to the connector breaking device, wherein the connector breaking device includes: a push bar configured to move upwards inside a cartridge with a pressure applied due to swelling of the battery cell; a first elastic member configured to maintain an elastically compressed state in a direction opposite to the electrode lead and be restored when the push bar moves upwards; and a breaking unit configured to move toward the connector through an opening formed at a top end of the cartridge due to a restoring force of the first elastic member so as to cut off an electric connection between the connector and the electrode lead, wherein the cartridge is configured to accommodate the push bar, the first elastic member and the breaking unit, a push bar configured to move upwards inside a cartridge with a pressure applied due to swelling of the battery cell; a first elastic member configured to maintain an elastically compressed state in a direction opposite to the electrode lead and be restored when the push bar moves upwards; and a breaking unit configured to move toward the connector through an opening formed at a top end of the cartridge due to a restoring force of the first elastic member so as to cut off an electric connection between the connector and the electrode lead, wherein the cartridge is configured to accommodate the push bar, the first elastic member and the breaking unit, wherein the connector breaking device further includes a stopper configured to fix the breaking unit so that the first elastic member maintains a compressed state, the stopper releasing a fixed state of the breaking unit when the push bar is compressed due to swelling so that the breaking unit moves toward the connector due to the restoring force of the first elastic member, wherein the cartridge includes a guide rib formed to protrude from an inner surface thereof and inclined at a predetermined angle with respect to a horizontal line wherein the push bar includes a push rib extending upwards toward the guide rib and having one end located between the guide rib and the stopper, wherein when the push bar is compressed due to the swelling, the push rib changes a moving direction by the guide rib so that one end of the push rib applies a pressure to one end of the stopper, wherein the stopper moves with a pressure applied by the push rib to release the fixed state of the breaking unit.