A battery pack , comprising: a pack housing including a lower frame and a side frame ; and one or more battery modules accommodated in the pack housing , wherein the battery module includes: a plurality of cell stacks in which a plurality of battery cells are stacked in a first direction; and a plurality of end plates fastened to the lower frame , and wherein the plurality of end plates and the plurality of cell stacks are alternately disposed in the first direction, wherein the side frame includes a guide block that blocks spreading of high-temperature and highpressure gas or flame generated in one portion of the battery module to other portions of the battery module or other battery modules , and protrudes in a second direction perpendicular to the first direction, wherein at least one of the plurality of end plates includes an insertion groove into which the guide block is inserted, wherein a venting passage having at least a portion extending in the first direction is formed in the side frame , wherein the side frame includes a plurality of openings communicating with the venting passage and an internal space (R) of the pack housing , and wherein the guide block is disposed between the plurality of openings . a pack housing including a lower frame and a side frame ; and one or more battery modules accommodated in the pack housing , wherein the battery module includes: a plurality of cell stacks in which a plurality of battery cells are stacked in a first direction; and a plurality of end plates fastened to the lower frame , and wherein the plurality of end plates and the plurality of cell stacks are alternately disposed in the first direction, wherein the side frame includes a guide block that blocks spreading of high-temperature and highpressure gas or flame generated in one portion of the battery module to other portions of the battery module or other battery modules , and protrudes in a second direction perpendicular to the first direction, wherein at least one of the plurality of end plates includes an insertion groove into which the guide block is inserted, wherein a venting passage having at least a portion extending in the first direction is formed in the side frame , wherein the side frame includes a plurality of openings communicating with the venting passage and an internal space (R) of the pack housing , and wherein the guide block is disposed between the plurality of openings . a plurality of cell stacks in which a plurality of battery cells are stacked in a first direction; and a plurality of end plates fastened to the lower frame , and wherein the plurality of end plates and the plurality of cell stacks are alternately disposed in the first direction, wherein the side frame includes a guide block that blocks spreading of high-temperature and highpressure gas or flame generated in one portion of the battery module to other portions of the battery module or other battery modules , and protrudes in a second direction perpendicular to the first direction, wherein at least one of the plurality of end plates includes an insertion groove into which the guide block is inserted, wherein a venting passage having at least a portion extending in the first direction is formed in the side frame , wherein the side frame includes a plurality of openings communicating with the venting passage and an internal space (R) of the pack housing , and wherein the guide block is disposed between the plurality of openings . <EOS>