To obtain multiplexed light rays having uniform light intensity by multiplexing light rays emitted from a plurality of light sources without using an optical means.

Using a multiplexer 4 in which optical waveguides 3 are integrated extending from the outgoing ends of a plurality of optical waveguides 3, the light rays made incident on the optical waveguides 3 is multiplexed to form multiplexed light rays. The multiplexed light rays emitted from the multiplexer 4 is made incident to a rod integrator 5 and output by uniformizing the light intensity of the multiplexed light rays.