  We present a map of the major part of the central molecular zone (CMZ) of
simultaneous observations in the NH3 (J,K) = (1,1) and (2,2) lines using the
Kagoshima 6-m telescope. The mapped area is -1.000 < l < 1.625 deg, -0.375 < b
< +0.250 deg. The kinetic temperatures derived from the (2,2) to (1,1)
intensity ratios are 20--80 K or exceed 80 K. The gases corresponding to
temperature of 20--80 K and > 80 K contain 75% and 25% of the total NH3 flux,
respectively. These temperatures indicate that the dense molecular gas in the
CMZ is dominated by gas that is warmer than the majority of the dust present
there. A comparison with the CO survey by Sawada et al. (2001) shows that the
NH3 emitting region is surrounded by a high pressure region on the l-v plane.
Although NH3 emission traces dense gas, it is not extended into a high pressure
region. Therefore, the high pressure region is less dense and has to be hotter.
This indicates that the molecular cloud complex in the Galactic center region
has a ``core'' of dense and warm clouds which are traced by the NH3 emission,
and an ``envelope'' of less dense and hotter gas clouds. Besides heating by
ambipolar diffusion, the hot plasma gas emitting the X-ray emission may heat
the hot ``envelope''.
