  Recently we made a proposal for realization of an effective BRS symmetry
along the Wilsonian renormalization group flow. In this paper we show that the
idea can be naturally extended for the most general gauge theories. Extensive
use of the antifield formalism is made to reveal some remarkable structure of
the effective BRS symmetry. The average action defined with a continuum analog
of the block spin transformation obeys the quantum master equation (QME),
provided that an UV action does so. We show that the RG flow described by the
exact flow equations is generated by canonical transformations in the
field-antifield space. Using the relation between the average action and the
Legendre effective action, we establish the equivalence between the QME for the
average action and the modified Ward-Takahashi identity for the Legendre
action. The QME remains intact when the regularization is removed.
