To prevent a sheet lay, suction wheels or the like from being damaged by corners and the like which are carelessly left on a paper pile board.

A suction means 15E is provided on an upstream side in a sheet conveying direction of the paper pile board and on a downstream side of a sheet of paper 6 to be conveyed. A suction belt 16 having a suction surface 16a is provided for sucking the sheet 6 in a slidable contact state. A pair of emergency limit switches 30 which detect the corner or the like left on the paper pile board at the two end sides in the widthwise direction of the sheet 6 to be conveyed. A detection bar 33 extends in the widthwise direction of the sheet 6 to be conveyed, and a dog 35 is provided at the two end sides for actuating an actuating part 30a of the emergency limit switches 30. The detection bar 33 can be movable in the up-and-down direction by means of four small shafts 40 and is pivotally supported in the widthwise direction of the sheet 6.