Аннотация:It is shown on the basis of magnetostriction measurements of the compound ErFe3 that, in a magnetic field, angular structures and also a reorientation of the magnetic moments of the sublattices appear in the vicinity of the magnetic compensation temperature of this ferrimagnet. A theory is developed for the magnetostriction of a uniaxial ferrimagnet with its magnetic phase diagram taken into account which describes the experimental results obtained well.