Optical integrator and video projection device using same

The purpose of the present invention is to provide a small optical integrator for increasing color mixing and homogeneity. This optical integrator is characterized in that: the optical integrator is provided with a light incident surface and exit surface (002, 003) and side surfaces (004, 005, 006, 007) linking the incident surface and the exit surface; the inside thereof is filled with a light guide member having a certain refractive index; the light guide member includes scattering particles that scatter light and have a refractive index different from the refractive index of the light guide member; light incident to the incident surface is propagated in the direction of the exit surface while being scattered by the scattering particles within the light guide member; and part of the scattered light that is scattered is propagated while being confined within an optical detector by the total internal reflection of the side surfaces so as to be guided to the exit surface.