Abstract
The noncommutative Hardy spaces H∞(α) and H1(α) are introduced with respect to a σ-weakly continuous flow α={αt} of *-automorphisms of a von Neumann algebra. In case that the algebra is α-finite the algebra H∞(α) becomes a maximal subdiagonal algebra. The concept of C*-subdiagonal algebras will also be given for C*-algebras as a noncommutative counterpart of the algebras of generalized analytic functions. Examples of maximal C*-subdiagonal algebras and their structures are discussed.