To provide a paper classification device by which paper sheets which possibly cause paper jamming are rejected.

A pattern of a slide 3 is projected onto paper by using a projection means, consisting of a light source 2, the slide 3 on which a pattern is formed, and a lens 4, forming the image of the pattern onto the paper. An image obtained by a CCD camera 5 picking up the pattern projected on the paper is analyzed by an image-processing unit 6 to obtain a degree of deformation of the paper 1. Depending on the degree of deformation, the device classifies the paper sheets as to papers used for a copying machine or a printer or the like and to papers which cannot be used by them.