  We report improved measurements of $B$ to pseudoscalar-vector decays
containing an $\omega$ meson in the final states. Our results are obtained from
a data sample that contains $388\times 10^{6}$ $B\bar{B}$ pairs accumulated at
the $\Upsilon(4S)$ resonance, with the Belle detector at the KEKB
asymmetric-energy $e^+ e^-$ collider. We measure the following branching
fractions: ${\mathcal B}(B^{+} \to \omega K^{+}) = [8.1\pm0.6({\rm
stat.})\pm{0.6}({\rm syst.})]\times 10^{-6}$, ${\mathcal B}(B^{+} \to \omega
\pi^{+}) = [6.9\pm{0.6}({\rm stat.})\pm{0.5}({\rm syst.})]\times 10^{-6}$, and
${\mathcal B}(B^{0} \to \omega K^{0}) = [4.4^{+0.8}_{-0.7}({\rm
stat.})\pm{0.4}({\rm syst.})]\times 10^{-6}.$ The partial width ratio
$\frac{\Gamma (B^{+}\to \omega K^{+})}{\Gamma (B^{0}\to \omega K^{0})}$ =
$1.8\pm0.4({\rm stat.})\pm0.1({\rm sys.})$. We also set the 90% confidence
level upper limit ${\mathcal B}(B^{0} \to \omega \pi^{0}) < 2.0\times 10^{-6}.$
In addition, we obtain the partial rate asymmetries ${\mathcal A}_{CP} =
0.05^{+0.08}_{-0.07}(\rm {stat.}) \pm 0.01(\rm {syst.})$ for $B^{+} \to \omega
K^{+}$, and ${\mathcal A}_{CP} = -0.02 \pm 0.09(\rm {stat.}) \pm 0.01(\rm
{syst.})$ for $B^{+}\to \omega \pi^{+}$.
