To provide an optical system in which efficiency of bringing out fluorescent light, emission light, illumination light or the like emitted from a light-emitting body can be significantly improved while reducing as much as possible a loss in the luminous energy due to absorption of light by the light-emitting body itself.

The optical system includes plate type optical members 1, 2 having side faces 11, 21 including elliptical faces 11a, 21a and conical faces 11b, 21b, upper faces 12, 22 and bottom faces 13, 23, respectively, wherein the bottom faces are stacked in a plane symmetry arrangement. A reflection region (A) having the same pattern and the same size as the upper faces 12, 22 is disposed between the bottom faces from the end of the elliptical face side toward the conical face side. The plate type optical member 1 has a groove 14 at the primary focus position of the elliptical form. Each plate type optical member 1, 2 has the primary focus point of the elliptical form coincident with the curvature center of the circular form, has the secondary focus of the elliptical form close to the conical face, and an aperture 15, 25 on the conical face near the secondary focus position of the elliptical form.