A transmission system formed by connecting sites through an optical fiber stores at least unique information of the transmission functional devices for each site, connection information, and information of wavelength resources that can be accommodated in the optical fiber in a facility DB as DB information D2. When the number of wavelengths of order information for requesting the number of wavelengths required for transmission of optical signals between sites is larger than the number of wavelengths that can be accommodated in the optical fiber of the DB information D2, the number of wavelengths for each of the transmission functional devices required for enabling the number of wavelengths of the order information D1 to be accommodated in the optical fiber is designed using the design unit. Designed numbers of wavelengths are configured in the corresponding transmission functional devices using the configuration unit.