An optical transmitting apparatus used in an optical communicating system in an optical communication network using a broad-band characteristic of fibers, which can transmit wavelength division multiplexed optical signals over the optical communication network, has an optical signal generating unit for generating optical signals for the respective plural opposite apparatus by using a combination of p (p; an integer not less than 2) wavelengths set in advance for each of the plural opposite apparatus, and a wavelength division multiplexing transmitting unit for wavelength division multiplexing the optical signals generated by the optical signal generating unit and transmitting the optical signals, thereby accommodating subscriber terminals larger in number than the number of times of wavelength division multiplexing while realizing privacy protection.