To improve binding efficiency by eliminating manual reversing and stacking work and automatically reversing the predetermined number of sheets on a conveyor when supplying folded cases made of corrugated fibreboard of uneven thickness and various size to a binder.

A reversing device having a plurality of parallel plate springs 30, which is formed with a hook-like hanging part 32 in a distal end thereof, is provided freely to move forward, backward, upward and downward over an intermediate area H of a lower stage belt 12 horizontally arranged from a case receiving side to a discharge side, and a first and a second upper stage belts 14 and 36 are provided in front and rear of the intermediate area H to form a pick-up feeding conveyor device. The first upper stage belt 14 is provided freely to move upward, downward, forward and backward in relation to the lower stage belt 12, and the second upper stage belt 36 is provided freely to move upward and downward in relation to the lower stage belt. The predetermined number of transfer cases on the belt are reversed in a progressing direction in the intermediate area H.