An optical branching/coupling device comprising: a first splitting means for splitting an optical signal from a first terminal station (A); a second splitting means for splitting an optical signal from a second terminal station (C); a wavelength selecting means for outputting, from a second output port, an optical signal on a first wavelength band (A1) and an optical signal on a third wavelength band (C2) that does not overlap the first wavelength band (A1), and outputting, from a first output port, an optical signal on a second wavelength band (A2) that does not overlap the first wavelength band (A1), based on the optical signal on the first wavelength band (A1) and the optical signal on the second wavelength band (A2) that are input to a first input port, and the optical signal on the third wavelength band (C2) that is input to a second input port, the optical signals of the first to the third wavelength band being derived from output of the first splitting means and output of the second splitting means , a crossbar switching means for outputting a first output signal and a second output signal, based on outputs of the first output port and the second output port; a first optical switching means for outputting, to the second terminal station (C), one of an optical signal split at the first splitting means and the first output signal of the crossbar switching means ; and a second optical switching means for outputting, to the third terminal station (B), one of an optical signal split at the second splitting means and the second output signal of the crossbar switching means . a first splitting means for splitting an optical signal from a first terminal station (A); a second splitting means for splitting an optical signal from a second terminal station (C); a wavelength selecting means for outputting, from a second output port, an optical signal on a first wavelength band (A1) and an optical signal on a third wavelength band (C2) that does not overlap the first wavelength band (A1), and outputting, from a first output port, an optical signal on a second wavelength band (A2) that does not overlap the first wavelength band (A1), outputting, from a second output port, an optical signal on a first wavelength band (A1) and an optical signal on a third wavelength band (C2) that does not overlap the first wavelength band (A1), and outputting, from a first output port, an optical signal on a second wavelength band (A2) that does not overlap the first wavelength band (A1), based on the optical signal on the first wavelength band (A1) and the optical signal on the second wavelength band (A2) that are input to a first input port, and the optical signal on the third wavelength band (C2) that is input to a second input port, the optical signals of the first to the third wavelength band being derived from output of the first splitting means and output of the second splitting means , the optical signal on the first wavelength band (A1) and the optical signal on the second wavelength band (A2) that are input to a first input port, and the optical signal on the third wavelength band (C2) that is input to a second input port, the optical signals of the first to the third wavelength band being derived from output of the first splitting means and output of the second splitting means , a crossbar switching means for outputting a first output signal and a second output signal, based on outputs of the first output port and the second output port; a first optical switching means for outputting, to the second terminal station (C), one of an optical signal split at the first splitting means and the first output signal of the crossbar switching means ; and a second optical switching means for outputting, to the third terminal station (B), one of an optical signal split at the second splitting means and the second output signal of the crossbar switching means . <EOS>