A technique to heal fatigue damage in a stainless steel by controlling high-density electric current have been studied. However, these mechanism was not investigated in detail. In this study, dislocation motion was observed by transmission electron microscope (TEM) before and after applying electric current in a sample cut out from fatigue specimen. When the current application direction was opposite, the dislocation motion direction also became opposite. The experimental results showed that dislocation motion was caused by electrons.