There is presented results studying of changes of the domain structure of a planar square microparticle with dimensions 7.5 × 7.5 × 0.04 μm under uniaxial mechanical stress. Microparticles were made from following materials: permalloy (18% Fe, 82% Ni), permendur (50% Co, 50% Fe), halfenol (16% Ga, 84% Fe), Ni, terfenol (Tb0.3Dy0.7Fe1.92). It was concluded about promising of using these materials for creating microsensors of mechanical stress and for creating straintronic devices for processing and storing information.