It is an object of the present invention to secure safety of a human body accessible to a side of a delivery conveyor during operations of a printing machine. Each of sensors 79 in an area sensor that form a sensing area B to prevent access of a human body to the side of a delivery conveyor (a chain gripper or the like) is arranged on the side of the delivery conveyor of a delivery unit in a paper ejector 7. Sensing operations of some of the sensors 79 in the area sensor are controlled to be turned off by a control device 9 in conjunction with a preset instruction of presetting a size of sheet and operations of the printing machine to sense access of a human body to the side of the delivery conveyor and prevent a sheet from being sensed by the sensors 79 during printing operations.
