Paper feeder and image forming apparatus

A paper feeder includes: first and second accommodation units which are arranged side by side in a casing along a recording paper conveyance direction and in which recording paper is loaded in a specified accommodation orientation; and an erroneous loading detection unit which is provided in a non-loaded region between the first and second accommodation units, detects whether or not the recording paper is loaded, and detects recording paper accommodated in an orientation other than the specified accommodation orientation, wherein the paper feeder can shift a bundle of the recording paper loaded in the second accommodation unit to the first accommodation unit arranged on a downstream side of the recording paper conveyance direction.