MULTIPLE RECORDING PREVENTING DEVICE

PROBLEM TO BE SOLVED: To prevent a multiple-recording even in the case where the direction of the recording papers to be recovered is irregular and also recording paper is reversely set in a paper feeding cassette, when using the rear side of the paper. SOLUTION: When the recording paper 18 is in carrying, the transfer surface of the recording paper 18 on which a toner image should be transferred is irradiated with the light emitted from the linear like light source of a rear paper detecting sensor 13, then, the reflected light is received by a solid-state image pick-up device. It is decided by the rear paper deciding means whether the image is already formed on the transfer surface of the recording paper 18 or the paper is blank based on a dignal from the solid-state image pick-up device. In the case of judging that the image is already formed on the transfer surface of the recording paper 18, the carrying path switching mechanism part 12 is switched to a rear paper carrying guide 16 side by a switching control part, then, the recording paper in carrying is discharged to a rear paper tray 17 through the rear paper carrying guide 16.