This study evaluated the compression force at the L5/S1 disc using back strength and IEMG(Integrated Electromyography). We divided the distance into one-half, three-fourth and full, measured the back strength. The results showed significant difference much among the cases. IEMG values were analyzed under the condition of fixed vertical factor, two horizontal factors, and 2 times per minute for the stoop posture. As the result, there are significant differences between horizontal distance 35cm and 55cm. This result showed that back strength decreased and the motor units of erector spinae muscle increased as the horizontal distance increased. Therefore, decreasing the horizontal distance to decrease compression force at L5/S1 is important on preventing a low back pain. Also, by using these data for prediction musculoskeletal disorders if we design equipment, machine and apparatus for human welfare, we can give advantage of prevention of low back pain much. We will be able to apply these data to work method or workplace lay-out.