A bracket device of a slide rail mechanism , comprising: an auxiliary supporting frame ; and: a bracket mounted to the auxiliary supporting frame ; an extension supporting frame movable relative to a rail member of the slide rail mechanism ; and a reinforcing member connected to the extension supporting frame , wherein the auxiliary supporting frame is movable relative to the extension supporting frame ; wherein one of the auxiliary supporting frame and the bracket comprises a first wall section and a second wall section , a space is defined between the first wall section and the second wall section , the bracket and the auxiliary supporting frame are movable relative to each other through the space ; wherein the bracket comprises a first supporting protrusion located at one of an upper side and a lower side of the space for supporting the second supporting frame ; wherein the auxiliary supporting frame comprises a front supporting protrusion located at the other one of the upper side and the lower side of the space for supporting the bracket ; and wherein one of the extension supporting frame and the auxiliary supporting frame comprises an upper supporting wall , a lower supporting wall and a longitudinal wall connected between the upper supporting wall and the lower supporting wall , a passage is defined by the upper supporting wall , the lower supporting wall and the longitudinal wall , the upper supporting wall and the lower supporting wall are movable relative to each other through the passage , the extension supporting frame comprises a second supporting protrusion located at one of an upper side and a lower side of the passage for supporting the auxiliary supporting frame , the auxiliary supporting frame comprises a rear supporting protrusion located at the other one of the upper side and the lower side of the passage for supporting the extension supporting frame . a bracket mounted to the auxiliary supporting frame ; an extension supporting frame movable relative to a rail member of the slide rail mechanism ; and a reinforcing member connected to the extension supporting frame , wherein the auxiliary supporting frame is movable relative to the extension supporting frame ; wherein one of the auxiliary supporting frame and the bracket comprises a first wall section and a second wall section , a space is defined between the first wall section and the second wall section , the bracket and the auxiliary supporting frame are movable relative to each other through the space ; wherein the bracket comprises a first supporting protrusion located at one of an upper side and a lower side of the space for supporting the second supporting frame ; wherein the auxiliary supporting frame comprises a front supporting protrusion located at the other one of the upper side and the lower side of the space for supporting the bracket ; and wherein one of the extension supporting frame and the auxiliary supporting frame comprises an upper supporting wall , a lower supporting wall and a longitudinal wall connected between the upper supporting wall and the lower supporting wall , a passage is defined by the upper supporting wall , the lower supporting wall and the longitudinal wall , the upper supporting wall and the lower supporting wall are movable relative to each other through the passage , the extension supporting frame comprises a second supporting protrusion located at one of an upper side and a lower side of the passage for supporting the auxiliary supporting frame , the auxiliary supporting frame comprises a rear supporting protrusion located at the other one of the upper side and the lower side of the passage for supporting the extension supporting frame . <EOS>