A small illumination apparatus including an optical member less affected by heat from a light source is disclosed. The illumination apparatus has a light source and an optical member closer to a light irradiation side than the light source and having an entrance surface formed as a refractive surface. The entrance surface has a first area receiving a first light component emitting from the light source at an angle smaller than a first angle with respect to an irradiation optical axis and a second area receiving a second light component emitting at an angle larger than the first angle with respect to the irradiation optical axis. The second area is positioned closer to the light source than the first area in the irradiation optical axis direction. Each of the first and second areas is formed a flat surface or a curved surface having a concave shape facing the light source.