Patent attributes
Provided is an illumination optical system for endoscope having high light utilization efficiency. The illumination optical system for endoscope which is provided in contact with an end surface of a light guide at a distal end portion of an insertion part of an endoscope, includes a diffusion plate that is provided on the end surface of the light guide and that diffuses light from the light guide, in which the diffusion plate has a diffusion surface that is formed on a surface on a side of the light guide and a light guide unit that guides light diffused on the diffusion surface, the diffusion surface consists of a holographic diffusion plate, and the light guide unit consists of sapphire glass.