An light input/output unit has at least three first ports, including a first input port for inputting light and a first output port for outputting light; at least three second ports, including a second input port for inputting light and a second output port for outputting light; and an alignment port for inputting and outputting alignment light. An optical axis of the input/output light of the first port and an optical axis of the input/output light of the second port differ from each other. The dispersive element changes the optical axes of input/output lights of the first and second ports by an angle corresponding to a wavelength. The light deflective element has a first part for directing the light from the first input port to the first output port and a second part for directing the light from the second input port to the second output port.