A transfer device for transferring flat boxes contained internally of a carton to an inlet line of a boxing machine, comprising: a positioning station of a carton, for receiving a carton with a relative upper face open and internally containing flat boxes which are predisposed, neared and flanked to one another, to form batteries of boxes which are arranged one above another internally of the carton and each contained internally of a relative containing flap, the positioning station being predisposed with respect to the inlet line of the boxing machine so as to receive the carton and to halt the carton in a halted position with a relative transversal wall facing towards the inlet line and with the open upper face in front of and substantially at a same level as a start of an inlet line; raising means, associated to the positioning station of the carton, which are configured and predisposed so as, time by time, to raise the batteries of boxes present internally of the carton so that a battery of boxes at a time is positioned in a waiting position beyond the open upper face of the carton in front of the start of the inlet line of the boxing machine; wherein the positioning station further comprises a rest plane and conveying means of the carton for conveying the carton with the open upper face above the rest plane; characterised in that it comprises: a frame predisposed so as to be activatable in translation above the positioning station of the carton and the inlet line of the boxing machine between a first position, wherein the frame is situated above the waiting position in which the raising means time by time raise a battery of boxes beyond the open upper face of the carton, and a second position in which the frame is situated above the inlet line of the boxing machine; gripping means (31, 32) mounted and predisposed on the frame so as to be activatable both for gripping and retaining a battery of boxes at the two ends (B1, B2) thereof and for releasing the battery of boxes, the gripping means (31, 32) are predisposed on the frame in such a way that, when the frame is in the first position above the waiting position, to be activatable for gripping and retaining the battery of boxes at the two ends (B1, B2) thereof, once the battery of boxes is raised by the raising means into the waiting position, and are also predisposed in such a way, when the frame is in the second position above the inlet line, as to be activated for releasing the battery of boxes into the inlet line, and in that the positioning station of the carton comprises maintaining means (14, 15) of the carton, for halting and keeping the carton halted on the rest plane in the halted position so that the raising means can raise the batteries of boxes with the carton maintained stably stationary on the rest plane. a positioning station of a carton, for receiving a carton with a relative upper face open and internally containing flat boxes which are predisposed, neared and flanked to one another, to form batteries of boxes which are arranged one above another internally of the carton and each contained internally of a relative containing flap, the positioning station being predisposed with respect to the inlet line of the boxing machine so as to receive the carton and to halt the carton in a halted position with a relative transversal wall facing towards the inlet line and with the open upper face in front of and substantially at a same level as a start of an inlet line; raising means, associated to the positioning station of the carton, which are configured and predisposed so as, time by time, to raise the batteries of boxes present internally of the carton so that a battery of boxes at a time is positioned in a waiting position beyond the open upper face of the carton in front of the start of the inlet line of the boxing machine; wherein the positioning station further comprises a rest plane and conveying means of the carton for conveying the carton with the open upper face above the rest plane; characterised in that it comprises: a frame predisposed so as to be activatable in translation above the positioning station of the carton and the inlet line of the boxing machine between a first position, wherein the frame is situated above the waiting position in which the raising means time by time raise a battery of boxes beyond the open upper face of the carton, and a second position in which the frame is situated above the inlet line of the boxing machine; gripping means (31, 32) mounted and predisposed on the frame so as to be activatable both for gripping and retaining a battery of boxes at the two ends (B1, B2) thereof and for releasing the battery of boxes, the gripping means (31, 32) are predisposed on the frame in such a way that, when the frame is in the first position above the waiting position, to be activatable for gripping and retaining the battery of boxes at the two ends (B1, B2) thereof, once the battery of boxes is raised by the raising means into the waiting position, and are also predisposed in such a way, when the frame is in the second position above the inlet line, as to be activated for releasing the battery of boxes into the inlet line, and in that the positioning station of the carton comprises maintaining means (14, 15) of the carton, for halting and keeping the carton halted on the rest plane in the halted position so that the raising means can raise the batteries of boxes with the carton maintained stably stationary on the rest plane.