Partitioning device configured to group products and advance them to a packaging machine, comprising a first towing element movable in an advancement direction, a plurality of first towed elements defining first housings for the products and connected in series with each other to the first towing element by means of rigid articulated connections being movable with it in the advancement direction, and first advancement means connectable to the first towing element to act on it by moving it in the advancement direction in such a way that also the first towed elements move in the advancement direction from a loading area, where the products can be loaded into the first housings, to an unloading area, where the products can be unloaded from the first housings and introduced into the machine.