  We examine the possibility for precise determination of |V_{ts}| (and
|V_{td}/V_{ts}|) from the exclusive decays, $B --> K \ell^+ \ell^-, B --> K^*
\ell^+ \ell^-$ (and $B --> \pi \ell^+ \ell^-, B --> \rho \ell^+ \ell^-$). We
show that the ratio |V_{ts}| can be extracted experimentally with a small
theoretical uncertainty from hadronic form--factors, if we {\bf appropriately
constrain} kinematical regions of $q^2$. We also give detailed analytical and
numerical results on the differential decay width $d\Gamma(B --> K^* \ell^+
\ell^-)/dq^2$, and the ratios of integrated branching fractions, ${\cal B}(B
--> \rho \ell^+ \ell^-)/{\cal B}(B --> K^* \ell^+ \ell^-)$. We estimate that
one can determine the ratio |V_{ts}| from those decays within theoretical
accuracy of $\sim 10%$.
