In longwall working face, it is essential to maintain roof strata in good condition, which is closely connected to safety and productivity of the face. Since the condition of the roof strata is greatly influenced by the resistance of the face props, it is important for strata control to use proper types of props in the proper way. From this point of view, underground investigations in order to confirm the resistance displayed by the face props were carried out. The resistance of a steel prop was obtained by measuring the strain of the prop, for which a couple of strain gauges were cemented onto the prop. This method of measuring the prop load proved to be pertinent in order to obtain the magnitude of the load acting on friction props and Dowty hydraulic props.