To continuously detect double feed with excellent accuracy even when changing a paper sheet storage means for feeding papers in an image forming device for continuously performing the paper feed from a plurality of paper sheet storage means.

An image forming device for recording an image on paper sheets which are fed and conveyed one by one from a plurality of paper feed trays comprises a paper sheet information detection means for detecting information on the paper sheets to be conveyed, and a double feed determination means for determining any double feed by comparing the result of detection of the detected paper sheet information with the reference value of the paper sheet information corresponding to each paper feed tray; and further comprises an initial reference value storage unit for storing the predetermined initial paper sheet information reference value X0 of the paper sheets, and a detected result storage unit for storing the paper sheet information detection results X1, X2, etc. The double feed determination means uses the initial paper sheet information reference value X0 as the paper sheet information reference value for the first paper sheet to be conveyed from each paper feed tray, and uses the paper sheet information reference value to be determined based on the paper sheet information detection results X1, X2, etc., for the second and subsequent paper sheets.