  We present the angular distribution of the rare B decay, $B \to K^* (\to K
\pi) \ell^+ \ell^-$. By studying the azimuthal angle distribution in the low
invariant mass region of dileptons, we can probe new physics effects
efficiently. In particular, this distribution is found to be quite sensitive to
the ratio of the contributions from two independent magnetic moment operators,
which also contribute to $B \to K^* \gamma$. Therefore, our method can be very
useful when new physics is introduced without changing the total decay rate of
the $b \to s \gamma$. The angular distributions are compared with the
predictions of the standard model, and are shown for the cases when the
afore-mentioned ratio is different from the standard model prediction.
