An optical transmission system having a linear repeater section that performs linear amplification of an optical signal, in which some functional redundancy is introduced to improve the reliability of long-distance signal transmission. The optical transmission line is segmented by regenerative repeater devices into a plurality of linear repeater sections, in each of which a plurality of linear optical amplifiers are deployed. The regenerative repeater devices have a signal regeneration unit that regenerates the received optical signals to compensate for their deterioration. The present invention eliminates RSOH termination and insertion functions from the regenerative repeater devices connected to at least one end of each linear repeater section. Further, the present invention deploys a signal regeneration unit in parallel with a linear optical amplifier within each linear repeater section. Still further, the present invention adds another signal regeneration unit to the existing signal regeneration unit as part of each regenerative repeater device connected to at least one end of each linear repeater section.