A method for analyzing the scattering of electromagnetic waves by a general bianisotropic slab is presented by extending the author's previous approaches for anisotropic, chiral, and those periodic media. The analysis is formulated in a unified matrix form, so that scattering characteristics can be obtained by system matrix calculations. The method can be extended straightforwardly to multilayerd and periodic structures. The scattering efficiencies are obtained for the incidence of not only linearly polarized waves but also circularly polarized waves.