To provide an image forming element capable of obtaining high resolution and high definition by an optical system and improving the latitude of the layout of a read-out optical system, and having high availability of light and being independent on stray light in spite of the compact image forming element.

A reflection type light converging pair 10 is an image forming element combining two reflection type light converging elements 11, 12 having a reflection surface by which a light beam emitted from one point of information 'o' or 'o'' on an original plane P is reflected as an almost parallel beam, the respective reflection surfaces are oppositely arranged so that one parallel beam is reflected by each reflection surface and each light converging point is made coincident with the other. Preferably, two reflection surfaces having the similar constitution are provided on a prism-like body. An image forming element suitable for an original read-out device is constituted by plurally arraying the reflection type light converging pairs or the prism-like bodies.