  We report on a Suzaku measurement of the shock feature associated with the
western radio relic in the merging cluster A3376. The temperature profile is
characterized by an almost flat radial shape with kT ~ 4 keV within 0.5 r200
and a rise by about 1 keV inside the radio relic. Across the relic region
(0.6-0.8 r200), the temperature shows a remarkable drop from about 4.7 keV to
1.3 keV. This is a clear evidence that the radio relic really corresponds to a
shock front possibly caused by a past major merger. The observed sharp changes
of the temperature and electron density indicate the Mach number M~3. The
radial entropy profile is flatter than the prediction (r^1.1) of numerical
simulations within 0.5 r200}, and becomes steeper around the relic region.
These observed features and time-scale estimation consistently imply that the
ICM around the radio relic has experienced a merger shock and is in the middle
of the process of dynamical and thermal relaxation.
