Effects of upper limb restraint on the sensorimotor network in the human brain were studied using transcranial magnetic stimulation (TMS) and somatosensory evoked potential (SEP). The subjects involved in this study were healthy individuals (TMS, 10 subjects; SEP, 9 subjects). Motor evoked potential (MEP) amplitudes by single-pulse TMS and SEP amplitudes by electrical stimulation of the median nerve were compared before and after a 10 hours restraint of the right upper limb. MEPs were recorded from the left and right first dorsal interosseous muscles. SEPs were recorded from Fz, on sensory areas for both hands, on the seventh spinous process, and from both Erb's points. The single-pulse TMS significantly reduced the MEP amplitude recorded in the constrained hand. In SEP, the potential of N30 component (derived from the supplementary motor area) recorded from Fz upon stimulation of the constrained hand increased significantly, whereas no significant changes were observed in the other potentials. The decrease in excitability of the primary motor area and activation of the supplementary motor area caused by the movement restriction are conceivable to be similar to the phenomenon observed in the recovery process from stroke motor paralysis. It is assumed that this phenomenon is regulated by the cortico-basal ganglia connection. However, details are unclear and further study is required.