In a wavelength division multiplexed transmission path, the used waveband can
be selected from the widest possible waveband among the S-band, C-band, and L-band.
The wavelength division multiplexed transmission path has a dispersion-compensating
transmission path comprising a dispersion-shifted fiber, which has positive chromatic
dispersion throughout a range of wavelengths from 1460 nm to 1630 nm, and one type
of dispersion-compensating fiber, or two or more types of dispersion-compensating
fiber having different chromatic dispersion having negative chromatic dispersion
in a compensation waveband, selected from the abovementioned range; the residual
chromatic dispersion of the wavelength division multiplexed transmission path is
adjusted so as to be greater than -1.0 ps/nm/km or equal to and less than or equal
to +1.0 ps/nm/km in a used waveband of the wavelength division multiplexed transmission
path, which is selected from the abovementioned range.