An optical device includes a light emitting surface, a lens mirror array having an incident surface that transmits light from the light emitting surface and converges the light, an emission surface that emits the light incident through the incident surface, and a plurality of reflecting surfaces that reflect the light incident through the incident surface toward the emission surface, and an image plane where an image of the light emitted through the emission surface is formed. The light emitting surface and the image plane are disposed nonparallel to each other so that an imaginary first plane parallel to the light emitting surface and an imaginary second plane parallel to the image plane intersect at a side of the plurality of reflecting surfaces.