A wavelength routing SW is a large-scale optical switch device of a conventional technique, and it requires as many wavelength-tunable light sources as the number of input ports. For the wavelength-tunable light sources to achieve a stable oscillating operation across a wide wavelength range, a complicated control mechanism is necessary. This has been an obstacle in providing a large-scale optical switch device in terms of cost and circuit scale. A wavelength routing SW in the present disclosure includes N wavelength group generators, a splitting-selection unit, and MN tunable filters. Each wavelength group generator includes M fixed-wavelength light sources. Inexpensive general-purpose devices that require no control mechanism for wavelength tuning can be used as the fixed-wavelength light source. The channel loss in the optical switch device can also be reduced by using light sources with a limited narrow range of tunable wavelengths and the wavelength-dependent output port selecting function of an AWG.