The improved illuminating apparatus comprises a spheroidal mirror, a light source, a spherical mirror and a condenser lens. The spheroidal mirror has such a shape that it is deficient of a portion that would otherwise reflect light that illuminates any portions other than the object to be illuminated, and that the light from the light source which is directed toward said missing portion is reflected by the spherical mirror positioned on the rear side of said missing portion as seen from the light source and makes another reflection by that part of the spheroidal mirror which faces away said missing portion, thereby illuminating the object. The light source is positioned at the first focal point of the spheroidal mirror in such a way that it faces the mirror, and the spherical mirror is positioned in such a way that its reflecting face lies at the second focal point of the spheroidal mirror. An open window for the exit of light beams is provided in the spherical mirror at a position near the second focal point of the spheroidal mirror, and the condenser lens is provided further ahead of the open window (closer to the object to be illuminated).