BATTERY PACK INCLUDING BATTERY MODULE

Discussed is a battery pack having a mounting structure including: a frame having a body portion with a plate placed horizontally, and sidewalk bent from opposite ends of the body portion and extending upward to form an inner space above the plate, and a battery module accommodated in the inner space of the frame, and including: a plurality of cylindrical battery cells; a module case having a plurality of hollow tubes into which the plurality of cylindrical battery cells standing upright in an upper and lower direction are inserted; and a connection portion configured to connect the plurality of hollow tubes to each other.