  RX J1856.5$-$3754 is the brightest and nearest ($\sim 120$ pc) source among
thermally emitting isolated neutron stars. Its spectra observed with {\sl
XMM-Newton} and {\sl Chandra} satellites are well-fitted with the
two-temperature ($kT^\infty \sim$ 32 and 63 eV) blackbody model. Fitting ten
sets of the data from {\sl Suzaku} XIS0, XIS1, XIS3 and {\sl XMM-Newton}
EPIC-pn with the two-temperature blackbody model, we discover an excess
emission, 16--26\% in 0.8--1.2\,keV. We examine possible causes of this
keV-X-ray excess; uncertainty in the background, pile up of the low energy
photons and confusion of other sources. None of them succeeds in explaining the
keV-X-ray excess observed with different instruments. We thus consider this
keV-X-ray excess is most likely originated in RX J1856.5$-$3754. However, it is
difficult to constrain the spectral shape of the keV-X-ray excess. The third
blackbody component with $kT^\infty = 137^{+18}_{-14}$ eV, additional power-law
component with a photon index $\Gamma = 3.4^{+0.5}_{-0.6}$, or Comptonization
of blackbody seed photons into power-law with a photon index $\Gamma_c =
4.3^{+0.8}_{-0.8}$ can reproduce the keV-X-ray excess. We also search for the
periodicity of 0.8--1.2\,keV data, since 7.055 s pulsation is discovered from
0.15--1.2\,keV band in the XMM Newton EPIC-pn data ($\sim$1.5\%). We only
obtain the upper limit of pulsed fraction $<$ 3\% in the keV-X-ray excess. We
shortly discuss the possible origin of the keV-X-ray excess, such as
synchrotron radiation and Comptonization of blackbody photons.
