To make an image projection device highly efficient.

Reflection polariscope 220 using double lightness reinforced film transmits P-polarized component and reflects S-polarized component of a beam of light from a highly efficient source of light 210. The transmitted P-polarized component is radiated onto an optical path to the screen via a mirror 250 and a projection lens 260. The reflected S-polarized light goes to a beam splitter/combiner 230 (hereinafter, combiner), wherein the light is split into blue, green, and red beams of light, and each of these light beams is radiated to reflection polarized light LCD 241 to 243 from a first to third surfaces of the combiner. These reflection polarized light LCDs polarize rays of a blue, green, and red light to return them to the combiner. The returned light is united by the combiner again, and P-polarized light is transmitted and S-polarized light is reflected by the reflection polariscope 220. P-polarized component is radiated via the projection lens 260. Efficiency improves by polarizing and reusing a undesired polarized component.