An optical unit includes one or more optical elements. At least one 40 of the optical elements has: an optical functional surface, that refracts incident light, within an effective diameter; and a rough surface 49 formed on an optical functional surface 42b that is formed outside the effective diameter and that scatters the incident light which has been internally reflected. With this configuration, light which is incident on the optical element and which may generate flare or the like when it is internally reflected by the optical functional surface outside the effective diameter is scattered by the rough surface formed on the optical functional surface outside the effective diameter. Therefore, generation of the flare or the like is suppressed. Also, since the optical unit is constituted by such an optical element having the rough surface, generation of the flare or the like is suppressed.