An optical unit includes: a light source; a rotating reflector configured to be rotated in a single direction with the rotational axis as the center of rotation while reflecting light emitted from the light source; and a projector lens configured to project light reflected by the rotating reflector in the light irradiation direction. The projector lens has a first lens region LR1 that defines the first focal plane and a second lens region that defines the second focal plane that differs from the first focal plane. The light source is arranged such that, when the rotating reflector is set to the first rotational position, its virtual position is in the vicinity of the focal plane, and such that, when the rotating reflector is set to the second rotational position, its virtual position is in the vicinity of the focal plane.