PURPOSE: To provide the optical branching device which stably branches light having necessary intensity and improves the utilization efficiency of the light as to an optical branching device which branches light from incident light.

CONSTITUTION: This device has a polarized wave control means 10 which controls the polarization state of the incident polarized light so that a TE polarized wave component and a TM polarized wave component has a specific intensity ratio and a polarized wave separating means 14 which demultiplexes the light whose polarization state is controlled by the polarized wave control means 10 into the TE polarized wave component and TM polarized wave component; and the TE polarized wave component or TM polarized wave component having specific intensity is branched from the incident light.