Abstract: A carton unfolding machine reliably unfolds folded carton blanks. The blanks are continuously propelled horizontally by stripper fingers along a first support with the flaps extending transversely to the direction of motion. Blocks in the path of the flaps raise the trailing flaps slightly relative to the plane of the blank sides and leading flaps. The blanks pass spring plates that enter slits between the trailing and leading upper flaps to support the trailing upper flaps. The first support terminates under the spring plates, so that the blank is supported only at the trailing upper flaps by the spring plates and by the stripper fingers. The unsupported blank leading edge tips due to gravity, thus slightly unfolding the blank. Continued motion by the stripper fingers pushes the blank out of contact with the second support, and the leading edge falls to a carrier.