  We report the observation of a narrow state decaying into $J/\psi\pi^+\pi^-$
and produced in $220 pb^{-1}$ of $\bar{p} p $ collisions at $\sqrt{s}=1.96 TeV$
in the CDF II experiment. We observe $ 730 \pm 90 $ decays. The mass is
measured to be $3871.3 \pm 0.7 (stat) \pm 0.4 (syst) MeV/c2$, with an observed
width consistent with the detector resolution. This is in agreement with the
recent observation by the Belle Collaboration of the X(3872) meson.
