Various constitutive models for the description of the elastoplastic deformation with an anisotropic hardening and also a transition from the elastic to the distinct-yield (fully-plastic) state have been proposed in the past. Among them the two- or multi-surface theory with plural stratified yield surfaces which has been extended from the kinematic hardening model would be one of the most available models, and many constitutive equations have been presented using that theory. None of them have been formulated, however, in mathematically rational forms applicable to the generalized materials with not only hardening but also softening behaviours. In this paper, a reasonable formulation of the two- and the multisurface theories will be given by deriving the mathematical condition which must be satisfied in order that the surfaces do not intersect each other at their relative translation and which will be called a “non-intersection condition” and by assuming a reasonable measure to represent the degree of distance from the distinctyield state in the two-surface theory. Among them the two-surface theory may be simple enough to be adopted in numerical analyses of practical problems in engineering.