To provide a polarized wave analyzer capable of analyzing and measuring the real-time polarization state at the using point of time of light, and keeping in the specific polarization state for long hours by installing a polarized wave control part.

This device includes a light branching means 2 for branching input light entering from a light input part, and has a light output part for supplying the polarized wave analyzer 1 with a part of light branched by the branching means, and outputting residual light to the outside. In the device, a polarized wave controller 6 is provided in the preceding step of a light branching element, and the polarized wave controller is controlled corresponding to polarization information from the polarized wave analyzer, to thereby keep in an optional polarization state.