  We present in this letter a high resolution (22'' FWHM) extended map at 2.1mm
of the Sunyaev-Zel'dovich effect toward the most luminous X-ray cluster,
RXJ1347-1145. These observations have been performed with the DIABOLO
photometer working at the focus of the 30m IRAM radiotelescope. We have derived
a projected gas mass of $(1.1 \pm 0.1)\times 10^{14} h_{50}^{-5/2}$M$_{\odot}$
within an angular radius of $\theta=74''$ (ie: projected radius of 0.6Mpc,
$H_{0}=50$km/s/Mpc, $\Omega_m=0.3$, $\Omega_\Lambda=0.7$). This result matches
very well the expected gas mass from the cluster models of X-ray data. With an
unprecedented sensitivity level our measurement does not show significant
departure from a spherical distribution. The data analysis also allows us to
characterize the 2.1mm flux of a well known radio source lying in the center of
the cluster: $F_{RS}(2.1\textrm{mm})=5.7\pm 1.6$mJy.
