A battery cell structure comprising battery cells connected to each other via a battery cell connector (100, 200, 300, 400), the battery cell connector (100, 200, 300, 400) being generally formed so as to have a hexahedral shape, the battery cell connector (100, 200, 300, 400) comprising: a lower mounting unit (110, 210, 310, 410) formed in an upper surface thereof, the lower mounting unit (110, 210, 310, 410) being configured to mount a lower part of a cylindrical battery cell (610, 620); an upper mounting unit (113, 213) formed in a lower surface thereof, the upper mounting unit (113, 213) being configured to mount an upper part of another cylindrical battery cell (610, 620); and a connection unit (120, 220, 320, 420) formed at a front surface, a rear surface, a left surface, and a right surface thereof, the connection unit (120, 220, 320, 420) being configured to electrically and physically connect the battery cell connector (100, 200, 300, 400) to another battery cell connector (100, 200, 300, 400), wherein the lower mounting unit (110, 210, 310, 410), the upper mounting unit (113, 213), and the connection unit (120, 220, 320, 420) include a connection part electrically connected to the inside of the battery cell connector (100, 200, 300, 400), and the connection part is electrically connected to a plurality of battery cells while being connected to electrode terminals of the cylindrical battery cell (610, 620), wherein the upper mounting unit (113,213) is provided in the interior of the battery cell connector (100,200,300,400) with a slit mounting unit (130, 230) configured to fix a cylindrical battery cell (610, 620) having a fixing slit (512, 522) formed therein, and an interior of each of the lower mounting unit (110, 210, 310, 410) and the upper mounting unit (113, 213) is formed so as to have a shape of a circular recess with a bottom and wherein each of the lower mounting unit (110, 210, 310, 410) and the upper mounting unit (113, 213) is provided in the interior thereof with a means configured to fix a cylindrical battery cell (610, 620) mounted thereto, wherein each of the lower mounting unit (110, 210, 310, 410) and the upper mounting unit (113, 213) is provided on an inner sidewall thereof with a protruding structure (111, 211, 311, 411) configured to fix a cylindrical battery cell (610, 620) mounted thereto. a lower mounting unit (110, 210, 310, 410) formed in an upper surface thereof, the lower mounting unit (110, 210, 310, 410) being configured to mount a lower part of a cylindrical battery cell (610, 620); an upper mounting unit (113, 213) formed in a lower surface thereof, the upper mounting unit (113, 213) being configured to mount an upper part of another cylindrical battery cell (610, 620); and a connection unit (120, 220, 320, 420) formed at a front surface, a rear surface, a left surface, and a right surface thereof, the connection unit (120, 220, 320, 420) being configured to electrically and physically connect the battery cell connector (100, 200, 300, 400) to another battery cell connector (100, 200, 300, 400), wherein the lower mounting unit (110, 210, 310, 410), the upper mounting unit (113, 213), and the connection unit (120, 220, 320, 420) include a connection part electrically connected to the inside of the battery cell connector (100, 200, 300, 400), and the connection part is electrically connected to a plurality of battery cells while being connected to electrode terminals of the cylindrical battery cell (610, 620), wherein the upper mounting unit (113,213) is provided in the interior of the battery cell connector (100,200,300,400) with a slit mounting unit (130, 230) configured to fix a cylindrical battery cell (610, 620) having a fixing slit (512, 522) formed therein, and an interior of each of the lower mounting unit (110, 210, 310, 410) and the upper mounting unit (113, 213) is formed so as to have a shape of a circular recess with a bottom and wherein each of the lower mounting unit (110, 210, 310, 410) and the upper mounting unit (113, 213) is provided in the interior thereof with a means configured to fix a cylindrical battery cell (610, 620) mounted thereto, wherein each of the lower mounting unit (110, 210, 310, 410) and the upper mounting unit (113, 213) is provided on an inner sidewall thereof with a protruding structure (111, 211, 311, 411) configured to fix a cylindrical battery cell (610, 620) mounted thereto.