A secondary battery pack comprising: - secondary battery modules including: - a plurality of secondary battery cells stacked in parallel to each other in a vertical direction, - a cover covering an uppermost surface of the secondary battery cells and with one side and another side in a horizontal direction, and - a switch installed at an upper side of one end in the horizontal direction of the cover; - a housing for accommodating the secondary battery modules therein; - a PRA (Power Relay Assembly) including a relay electrically connected to the secondary battery cells and switches, for transmitting charging power supplied from the outside to the secondary battery cells when the relay is in a close state and changing the relay to an open state when the switch is pushed; and - a battery management system for controlling the PRA; characterized in that - a support member is disposed at a central portion of the secondary battery cells and the cover in the horizontal direction, - the support member surrounds the central portions of the secondary battery cells and the cover in the horizontal direction, and the support member is configured in such way that the one side and the other side in the horizontal direction of the cover are capable of rotating up and down around the support member as a rotation axis; - and the switch is installed at an upper side of one side in the horizontal direction of the cover such that it is pushed when the one side and the other side in the horizontal direction of the cover are upwardly rotated according to pressure applied to an upper side from a lower surface of the cover when swelling occurs. - secondary battery modules including: - a plurality of secondary battery cells stacked in parallel to each other in a vertical direction, - a cover covering an uppermost surface of the secondary battery cells and with one side and another side in a horizontal direction, and - a switch installed at an upper side of one end in the horizontal direction of the cover; - a plurality of secondary battery cells stacked in parallel to each other in a vertical direction, - a cover covering an uppermost surface of the secondary battery cells and with one side and another side in a horizontal direction, and - a switch installed at an upper side of one end in the horizontal direction of the cover; - a housing for accommodating the secondary battery modules therein; - a PRA (Power Relay Assembly) including a relay electrically connected to the secondary battery cells and switches, for transmitting charging power supplied from the outside to the secondary battery cells when the relay is in a close state and changing the relay to an open state when the switch is pushed; and - a battery management system for controlling the PRA; characterized in that - a support member is disposed at a central portion of the secondary battery cells and the cover in the horizontal direction, - the support member surrounds the central portions of the secondary battery cells and the cover in the horizontal direction, and the support member is configured in such way that the one side and the other side in the horizontal direction of the cover are capable of rotating up and down around the support member as a rotation axis; - and the switch is installed at an upper side of one side in the horizontal direction of the cover such that it is pushed when the one side and the other side in the horizontal direction of the cover are upwardly rotated according to pressure applied to an upper side from a lower surface of the cover when swelling occurs.