A battery pack that protects an internal configuration from external impact and effectively prevents internal short circuit is disclosed. The battery pack includes 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 with a part bulging in an outer direction are formed.