The paper studies the micropolar theory of the elasto-viscoplastic medium. The main contribution of this paper consists in the derivation of the balance equations and the system of constitutive equations based on thermodynamic analysis for the case when the granule rotates during movement. The paper shows that, based on this assumption, the concept of voltage coupling, as well as the anisotropic stress tensor, can be arrived at in a natural way. Viscoplastic flow and possible applications of the theory to body mechanics were also studied. It is also shown that the presented theory can be an interesting model of soil-type materials.