A device for forming a space between groups of a predetermined number of overlapped sheets moving successively in a line. The device has a first conveyor for conveying sheets of a fixed length which are cut from a band sheet. A second conveyor is provided just beyond the delivery end of the first conveyor for receiving sheets from the first conveyor in overlapping relationship. A suction means is provided adjacent said second conveyor for temporarily holding a sheet on the second conveyor by suction. The second conveyor is movable in such a way that the upper run thereof is movable up and down above and below the level of the suction means. The second conveyor is normally above the suction means, but when a predetermined number of sheets has been delivered to the second conveyor, the second conveyor is lowered, and one of the sheets delivered thereto is held by suction from the suction means to delay its movement along the second conveyor momentarily, after which the second conveyor is again raised to release the delayed sheet from the suction means.