  A possibility to measure $\sin^22\theta_{13}$ using reactor neutrinos is
examined in detail. It is shown that the sensitivity $\sin^22\theta_{13}>0.02$
can be reached with 20 ton-year data by placing identical CHOOZ-like detectors
at near and far distances from a giant nuclear power plant whose total thermal
energy is 24.3 ${\text{GW}_{\text{th}}}$. It is emphasized that this
measurement is free from the parameter degeneracies which occur in accelerator
appearance experiments, and therefore the reactor measurement plays a role
complementary to accelerator experiments. It is also shown that the reactor
measurement may be able to resolve the degeneracy in $\theta_{23}$ if
$\sin^22\theta_{13}$ and $\cos^22\theta_{23}$ are relatively large.
