In order to maintain postural balance, the somatosensory system contributes to balance providing the information on each part of body and its relative position by the receptors of the muscles and joints spread throughout the body. The relationship between the somatosensory system and postural balance has been reported from the experiments that confirmed the increase of postural stability and the decrease of the body’s sway were achieved by stimulating somatosensory system. In this study, two hypotheses were established in order to investigate a sense of postural balance and to study human body reaction by quantitative somatosensory stimulation. The somatosensory stimulation system and brain wave analysis system were used and 7 male adults who are without any neurological diseases participated in the experiment. Somatosensory stimulation device was attached on the tibialis anterior tendon and the Achilles tendon of the subjects and sensory threshold (100%), sub-threshold (90%) and supra-threshold (110%) stimulation was applied. The course of changes in brain activities when the somatosensory stimulation was applied on the tibialis anterior tendon and Achilles tendon was similarly observed regardless of the intensity of somatosensory stimulation. And the tendency of amplitude change by somatosensory evoked potential was found in all experiment conditions similarly regardless of intensity of the somatosensory stimulation. The results of this study will become the useful material along with results from the previous studies, which can promote development of somatosensory stimulation devices for the enhancement in the sense of postural balance.