The invention provides a plate detecting device for an overlapping-feeding detecting device, which can reliably detect the overlapping transporting of the plates when in transporting, as well as a manuscript transporting device and an image processing device with a plate transporting device. A paper transporting device (1b) is provided with a paper pallet (11), a paper- rubbing roller (61), a paper-feeding roller (63), a division roller (64), a transporting roller (66a), a paper-storing roller (67), a paper-arraying roller (73), a passing detecting sensor (69), an overlapping-feeding detecting device (68) and a second detecting device (71). The recording paper is outputted by the paper-rubbing roller (61) from the paper pallet (11) according to the printed instruction of the customer. Therecording paper is transported to the paper-storing roller (67) through the paper-feeding roller (63), the division roller (64), the transporting roller (66a) and the passing detecting sensor. The recording paper is temporarily stopped due to the paper-storing roller (67), and then the overlapping feeding of the recording paper is detected by the overlapping-feeding detecting device (68).