The invention relates to a device for feeding sheet products into a thick sheet feeding machine comprising an insertion gantry (2), a feed carriage (3) sliding on rails (5), wherein the device comprises an insertion head (1) configured by a gantry formed by a crosspiece and support legs positioned on the rails (5); and a system of suction cups located in the crosspiece through a forward movement mechanism allowing it to move; an insertion module (6) moving vertically on guides of the insertion gantry (2), a base (4) for placing the sheets, and an alignment control device for aligning the sheets with respect to the insertion module (6), wherein the sheets are suctioned by the suction cups, which are moved by the forward movement mechanism in the direction of the insertion gantry (2).