  We report on a polarization measurement of inclusive $J/\psi$ mesons in the
di-electron decay channel at mid-rapidity at 2 $<p_{T}<$ 6 GeV/$c$ in $p+p$
collisions at $\sqrt{s}$ = 200 GeV. Data were taken with the STAR detector at
RHIC. The $J/\psi$ polarization measurement should help to distinguish between
different models of the $J/\psi$ production mechanism since they predict
different $p_{T}$ dependences of the $J/\psi$ polarization. In this analysis,
$J/\psi$ polarization is studied in the helicity frame. The polarization
parameter $\lambda_{\theta}$ measured at RHIC becomes smaller towards high
$p_{T}$, indicating more longitudinal $J/\psi$ polarization as $p_{T}$
increases. The result is compared with predictions of presently available
models.
