ATM switch

An ATM switch includes a plurality of input line corresponding units, a plurality of output line corresponding units, and a wavelength shifting unit. The wavelength shifting unit is arranged between the input line corresponding units and the output line corresponding units to shift optical signals having different wavelengths in a plurality of wavelength-multiplexed optical signals arriving from the input line corresponding units and output the wavelength-multiplexed optical signals. Each input line corresponding unit includes an input-side basic switch for distributing N (N is a positive integer) cells respectively input to input ports to N lines, an electro-optic converter for converting the cells into optical signals having different wavelengths in units of N lines, and a multiplexer for multiplexing the optical signals into one wavelength-multiplexed optical signal. Each output line corresponding unit includes a demultiplexer for demultiplexing the wavelength-multiplexed optical signal in units of wavelengths, an opto-electric converter for converting outputs from the demultiplexer into electrical signals, respectively, and an output-side basic switch for distributing the cells converted into the electrical signals to a plurality of output ports.