An endoscope apparatus having an insertion part which includes an object optical system in order to conduct measurements or stereoscopic-vision observations, using the object optical system with a moderate parallax, a moderate size of an image can be provided without making an endoscope thick in diameter. Also disclosed are treatments to enhance extractability of the diphosphite-containing compounds. If so, a display that illustrates and allows resolution of the conflict is automatically provided. The invention also includes insoluble polysaccharide particles for application to human skin.