To provide an optical unit configured to efficiently use light emitted from a light source.

The optical unit is constituted by arranging two reflection surfaces facing each other across a virtual surface. The reflection surface on one side includes: a hemispherical first reflection surface; and a second reflection surface as a paraboloid and having a first opening near the apex thereof. The reflection surface on the other side includes a third reflection surface as a paraboloid having a second opening near the apex thereof. The peripheral part of the first reflection surface comes in contact with the first opening. The second reflection surface and the third reflection surface are disposed so that the paraboloid apex of the second reflection surface may align with the focal position of the paraboloid of the third reflection surface, and the paraboloid apex of the third reflection surface may align with the focal position of the paraboloid of the second reflection surface. The first reflection surface and the second reflection surface are disposed so that the curvature center of the first reflection surface may align with the paraboloid apex of the second reflection surface. The optical unit includes a first refractive surface disposed closer to the first reflection surface than the virtual surface, and a second refractive surface disposed closer to the third reflection surface than the virtual surface.