  Non-relativistic QCD is applied for a lattice computation of the heavy-light
meson decay constant in quenched approximation at $\beta=6.0$. Clear signals
are obtained for the ground state at large times in the correlators, allowing a
reliable extraction of the decay constant. Estimating the current
renormalization factor by the tadpole improvement procedure, we find $f_{B}=$
164(17) MeV for the $B$ meson with $a^{-1}=$ 2.3 GeV, while an extrapolation to
the static limit yields $f_{B}^{\mbox{static}}=$ 247(26) MeV.
