A node device receives supervisory control information on a dedicated wavelength different from a wavelength of signal light, which is input from an input port together with the signal light, and extracts, from signal light to be output from an output port, information superposed on an optical main signal of the signal light. Then, it is confirmed whether or not the signal light to be output and the supervisory control information correspond by using the extracted information, and supervisory control information corresponding to the signal light to be output is transmitted on the dedicated wavelength from the output port.