  Locality is analyzed for Toda field theories by noting novel chiral
description in the conventional nonchiral formalism. It is shown that the
canonicity of the interacting to free field mapping described by the classical
solution is automatically guaranteed by the locality. Quantum Toda theories are
investigated by applying the method of free field quantization. We give Toda
exponential operators associated with fundamental weight vectors as bilinear
forms of chiral fields satisfying characteristic quantum exchange algebra. It
is shown that the locality leads to nontrivial relations among the ${\cal
R}$-matrix and the expansion coefficients of the exponential operators. The
Toda exponentials are obtained for $A_2$-system by extending the algebraic
method developed for Liouville theory. The canonical commutation relations and
the operatorial field equations are also examined.
