A battery cell structure comprising battery cells connected to each other via a battery cell connector , the battery cell connector being generally formed so as to have a hexahedral shape, the battery cell connector comprising: a lower mounting unit formed in an upper surface thereof, the lower mounting unit being configured to mount a lower part of a cylindrical battery cell ; an upper mounting unit formed in a lower surface thereof, the upper mounting unit being configured to mount an upper part of another cylindrical battery cell ; and a connection unit formed at a front surface, a rear surface, a left surface, and a right surface thereof, the connection unit being configured to electrically and physically connect the battery cell connector to another battery cell connector , wherein the lower mounting unit , the upper mounting unit , and the connection unit include a connection part electrically connected to the inside of the battery cell connector , and the connection part is electrically connected to a plurality of battery cells while being connected to electrode terminals of the cylindrical battery cell , wherein the upper mounting unit is provided in the interior of the battery cell connector with a slit mounting unit configured to fix a cylindrical battery cell having a fixing slit formed therein, and an interior of each of the lower mounting unit and the upper mounting unit is formed so as to have a shape of a circular recess with a bottom and wherein each of the lower mounting unit and the upper mounting unit is provided in the interior thereof with a means configured to fix a cylindrical battery cell mounted thereto, wherein each of the lower mounting unit and the upper mounting unit is provided on an inner sidewall thereof with a protruding structure configured to fix a cylindrical battery cell mounted thereto. a lower mounting unit formed in an upper surface thereof, the lower mounting unit being configured to mount a lower part of a cylindrical battery cell ; an upper mounting unit formed in a lower surface thereof, the upper mounting unit being configured to mount an upper part of another cylindrical battery cell ; and a connection unit formed at a front surface, a rear surface, a left surface, and a right surface thereof, the connection unit being configured to electrically and physically connect the battery cell connector to another battery cell connector , wherein the lower mounting unit , the upper mounting unit , and the connection unit include a connection part electrically connected to the inside of the battery cell connector , and the connection part is electrically connected to a plurality of battery cells while being connected to electrode terminals of the cylindrical battery cell , wherein the upper mounting unit is provided in the interior of the battery cell connector with a slit mounting unit configured to fix a cylindrical battery cell having a fixing slit formed therein, and an interior of each of the lower mounting unit and the upper mounting unit is formed so as to have a shape of a circular recess with a bottom and wherein each of the lower mounting unit and the upper mounting unit is provided in the interior thereof with a means configured to fix a cylindrical battery cell mounted thereto, wherein each of the lower mounting unit and the upper mounting unit is provided on an inner sidewall thereof with a protruding structure configured to fix a cylindrical battery cell mounted thereto. <EOS>