A battery pack comprising: a plurality of can type secondary batteries arranged to be laid down in a horizontal direction; a bus bar at least partially formed of an electrically conductive material to electrically connect the plurality of can type secondary batteries; at least one module case with an empty space formed inside to accommodate the plurality of can type secondary batteries; and an insulating tube configured to surround an outer wall of the module case and having an outer surface on which a plurality of embossing structures (E1, E2), each having a part bulging in an outer direction, are formed, wherein the module case comprises: a first case in which an empty space is formed to accommodate the plurality of can type secondary batteries, and a second case coupled to one side of the first case in a horizontal direction and in which an empty space is formed to accommodate the plurality of can type secondary batteries, and wherein the insulating tube comprises a heat shrinkable material that is heat shrunk such that the first case and the second case are tightly fixed to each other, wherein the insulating tube comprises a band portion formed in a part corresponding to a position between the first case and the second case, formed to have a greater thickness than other parts of the insulating tube, and extending in a band shape to surround an outside of the module case. a plurality of can type secondary batteries arranged to be laid down in a horizontal direction; a bus bar at least partially formed of an electrically conductive material to electrically connect the plurality of can type secondary batteries; at least one module case with an empty space formed inside to accommodate the plurality of can type secondary batteries; and an insulating tube configured to surround an outer wall of the module case and having an outer surface on which a plurality of embossing structures (E1, E2), each having a part bulging in an outer direction, are formed, wherein the module case comprises: a first case in which an empty space is formed to accommodate the plurality of can type secondary batteries, and a second case coupled to one side of the first case in a horizontal direction and in which an empty space is formed to accommodate the plurality of can type secondary batteries, and wherein the insulating tube comprises a heat shrinkable material that is heat shrunk such that the first case and the second case are tightly fixed to each other, wherein the insulating tube comprises a band portion formed in a part corresponding to a position between the first case and the second case, formed to have a greater thickness than other parts of the insulating tube, and extending in a band shape to surround an outside of the module case. a first case in which an empty space is formed to accommodate the plurality of can type secondary batteries, and a second case coupled to one side of the first case in a horizontal direction and in which an empty space is formed to accommodate the plurality of can type secondary batteries, and wherein the insulating tube comprises a heat shrinkable material that is heat shrunk such that the first case and the second case are tightly fixed to each other, wherein the insulating tube comprises a band portion formed in a part corresponding to a position between the first case and the second case, formed to have a greater thickness than other parts of the insulating tube, and extending in a band shape to surround an outside of the module case.