  The contribution of the Source Cosmic Rays (SCRs), confined in Supernova
Remnants, to the diffuse high energy \gr emission above 1 GeV from the Galactic
disk is studied. \grs produced by the SCRs have a much harder spectrum compared
with those generated by the Galactic Cosmic Rays which occupy a much larger
residence volume uniformly. SCRs contribute less than 10% at GeV energies and
become dominant at \gr energies above 100 GeV. The contributions from
$\pi^0$-decay and Inverse Compton \grs have comparable magnitude and spectral
shape, whereas the Bremsstrahlung component is negligible. At TeV energies the
contribution from SCRs increases the expected diffuse \gr flux almost by an
order of magnitude. It is shown that for the inner Galaxy the discrepancy
between the observed diffuse intensity and previous model predictions at
energies above a few GeV can be attributed to the SCR contribution.
