On a Si(111) surface, which is covered with the 1 x 1 structure at high temperature, the 7 x 7 structure appears when temperature is lower than the structural transition temperature (860 degrees C) . On the vicinal face, the 7 x 7 structure spreads from the upper side of the step edge. The diffusion coefficient on the 1 x 1 structure is larger than that on the 7 x 7 structure. During growth, due to the difference in the diffusion coefficient, step wandering occurs and grooves perpendicular to the steps are formed. When the direct electric current is added parallel to the step, the grooves are tilted. In this paper, with taking account of the drift of adatoms caused by the direct current, we study the possibility of tilting of the grooves.