The invention provides an optical system for image projection, wherein when used in an image projection apparatus, a screen-continuing portion (e.g., screen-underlying portion) of the apparatus can be reduced to a small size, or can be removed, and thereby the apparatus can be so compacted, and provides an image projection apparatus mounting such optical system. An optical system 10 for image projection including a lighting optical system 1 leading light from a light source 11 for lighting a display element 4 (or 4′), and a projecting optical system 3 for projecting projection light containing image information from the display element 4 (or 4′). The lighting optical system 1 is arranged such that a straight optical axis α from the light source 11 in the lighting optical system 1 is positioned in an area deviated from a luminous flux β of the projection light incident into the projecting optical system 3 toward an area where the projection light γ from the projecting optical system 3 passes. The image projection apparatus A (or B or C) mounting such optical system 10.