An optical unit includes first to third prisms. The first prism has a first coated surface configured to reflect illumination light in a first wavelength band, a first surface, and a first light transmitting surface. The second prism has a second coated surface configured to reflect the illumination light in a second wavelength band, a second surface, and a second light transmitting surface. The third prism has a third light transmitting surface, and a fourth light transmitting surface. The first prism is formed with normal lines of the first coated surface, the first surface, and the first light transmitting surface being out of coplanar with each other, and/or the second prism is formed with normal lines of the second coated surface, the second surface, and the second light transmitting surface being out of coplanar with each other.