The effects of pure shear stress on magnetization in nickel have been studied with a view to developing a theoretical understanding of the Matteucci effect, which is of great technological interest in the search for viable magnetic torque sensors. The effects of pure shear stress on a planar magnetic material and those due to torque applied to a rod are analogous in the sense that they can be described in terms of a pair of tensile and compressive stresses acting at 45° to the neutral axis of the plate or the rod axis. In this work the responses of nickel to shear stresses were studied under various dc applied fields. A model description was developed as a generalization of the theory of magnetomechanical effect to include shear stress. This theory can be used as an aid to interpretation of the experimental results.