  We develop perturbative QCD formalism for three-body nonleptonic $B$ meson
decays. Leading contributions are identified by defining power counting rules
for various topologies of amplitudes. The analysis is simplified into the one
for two-body decays by introducing two-meson distribution amplitudes. This
formalism predicts both nonresonant and resonant contributions, and can be
generalized to baryonic decays.
