PURPOSE: To decrease frequency of paper jam by judging a paper sheet delayed a fixed time for a set paper feed timing not to be a paper jam, feeding the delayed paper sheet in the subsequent copying cycle and judging a paper jam when it is over a fixed time.

CONSTITUTION: A paper sheet 4 drawn out by a feed roller 3 of a paper feeder 2 is prevented from multi-feeding by a handling portion 5, and then transported through transport rollers 6 and a paper jam detector 7 to a gate 8. The gate 8 is adapted to open in a fixed timing to transport the paper sheet 4 between a photoreceptor 1 and a transfer device 9, and a toner image is transferred onto the paper sheet 4. In this case, when the paper sheet 4 is delayed at the handling portion 5, if the delay is larger than a preset time t1 and smaller than a fixed time t2, the paper sheet 4 is stopped at the gate 8 until the first copying cycle is completed, and is used in the second copying cycle by opening the gate 8. Thus, the frequency of a paper jam is decreased.