PURPOSE: To detect the sheet clogging correctly and speedily by installing two sheet presence detecting means positioned along the axis direction on the downstream side of a rotary body and a sheet clogging detecting means for detecting the sheet clogging on the basis of the signal.

CONSTITUTION: When a paper sheet S is caught by a separating hook 3d, and hook jamming is generated, one top edge part Sa passes through a sheet presence detecting sensor 7a in a predetermined time, and is detected by the sensor 7a, and the other top edge part Sb passes through a sheet presence detecting sensor 7b at a delayed time, and is detected by a sensor 7b. It is judged by a sheet clogging detecting means 17 if the difference of the earliness of the sheet detecting time of the sensors 7a and 7b is over a prescribed time or not, and if the value is over the prescribed value, the sheet clogging due to the hook jamming is judged, and a sheet clogging signal is transmitted. Further, a signal for stopping the transport of the sheet S is sent by a sheet transport stop instruction means 19, and a drum transport motor of the copying machine body is stopped, and the transport of the sheet S is suspended.