A wavelength selective switch according to the present invention includes at least one input port for inputting wavelength-multiplexed light, a dispersive element which receives the light from the input port, and disperses the received light, a light converging element which converges dispersed light which has been dispersed for each wavelength, a light deflecting member having a plurality of reflecting optical elements which are capable of independently deflecting each dispersed light from the light converging element, and at least one output port which receives light which has been deflected by the light deflecting member. An area having a reflectivity higher than a central area of the reflecting surface is formed in at least a part of an end portion of the reflecting surface in the dispersive direction by the dispersive element.