Numerous theoretical and experimental studies of the effect of weak magnetic fields (MFs) on physical properties of nonmagnetic materials finally led to the development of a new direction in strength physics, i.e., spin micromechanics [1,2]. Since the discovery of the magnetoplastic effect (MPE) by V.I. Al'shits with colleagues in 1987 [3] and to date, the vast majority of studies have been performed on ionic crystals as the simplest model materials in which the effect of plastic ity variation upon exposure to weak MFs can be observed almost in its pure form [2]. According to cur rent concepts, an increase in the plasticity of nonmag netic ionic crystals by 50-100% in a weak (B < 0.1 T) magnetic field is associated with "switching" of spins of defects involved in plastic deformation, which results in dislocation release from pinning centers [2]. Variations in plasticity of solids upon exposure to MFs is observed not only in ionic crystals, but also in mate rials with other chemical bond types (covalent, ionic covalent, molecular, metallic, and even amorphous ones [4]). However, the MPE is probably least studied in diamagnetic metals as the most complex objects for such studies [5,6]. The MPE in metals is often masked and is significantly distorted by accompanying effects, such as vortex electric fields and currents, the electro plastic effect, and others. Nevertheless, in our opinion, the prospect of controlling the room temperature metal plasticity by the MF should stimulate such studies.In this paper, we present the results of the study of the effect of a weak dc MF on elastic and inelastic characteristics of a magnesium thermal beryllium condensate (MTC Be) in the temperature range of structural phase transformations in order to determine the possibility of controlling the plastic properties of this metal using a weak dc MF. When choosing the object and techniques of the study, we were guided by the following reasons. First, Be is a metal with diamag netic properties. Second, beryllium is a known struc tural material characterized by an increased brittleness at close to room temperatures [7]. The possibility of solving the beryllium brittleness problem using the MF seemed very promising. Especially since a number of extraordinary structural transformations take place in MTC Be in the temperature range of 50-400°C, which initiate a significant restructurization of the defect subsystem, accompanied by 20% softening of the effective shear modulus (G eff ) near 260°C [8-10]. As is known, the nonlinear behavior of G eff with varia tions in the temperature points to a significant insta bility of the dislocation-impurity system, which would allows us to satisfy the main condition of the MPE existence (resumed instability of the defect sub system [1]) by means of a simple thermal cycling in the above temperature range. Finally, since shear pro cesses dominate in Be structural transformations [10], the low frequency (~1 s -1 ) internal friction (IF) method with synchronous measurements of G eff has been chosen as the m...