  We have carried out a spectral analysis of the Suzaku X-ray data in the
0.4-12 keV range toward the shell-type very-high-energy {\gamma}-ray supernova
remnant RX J1713.7-3946. The aims of this analysis are to estimate detailed
X-rays spectral properties at a high angular resolution up to 2 arcmin, and to
compare them with the interstellar gas. The X-ray spectrum is non-thermal and
used to calculate absorbing column density, photon index, and
absorption-corrected X-ray flux. The photon index varies significantly from 2.1
to 2.9. It is shown that the X-ray intensity is well correlated with the photon
index, especially in the west region, with a correlation coefficient of 0.81.
The X-ray intensity tends to increase with the averaged interstellar gas
density while the dispersion is relatively large. The hardest spectra having
the photon index less than 2.4 are found outside of the central 10 arcmin of
the SNR, from the north to the southeast (~430 arcmin^2) and from the southwest
to the northwest (~150 arcmin^2). The former region shows low interstellar gas
density, while the latter high interstellar gas density. We present discussion
for possible scenarios which explain the distribution of the photon index and
its relationship with the interstellar gas.
