An optical system includes a first optical element including a first reflective area having a convex shape toward a magnification side, a second optical element including a second reflective area having a convex shape toward the magnification side, and a light shielding member disposed between the first optical element and the second optical element. Light from the magnification side travels to a reduction side through the second reflective area, the first reflective area, and a refractive area of the second optical element in order. The light shielding member is disposed between light entering the second reflective area and light entering the first reflective area in a first cross-section including an optical axis.