Surface mass transport of In film on vicinal Si(0 0 1) has been systematically investigated by a scanning Auger electron microscopy (SAM), low energy electron diffraction (LEED) and atomic force microscopy (AFM). It was observed that the temperature dependence of the mass transport shows the critical phenomenon. Above a critical temperature T-c, surface electromigration of the In film toward the cathode side dominated the surface mass transport on the vicinal Si(0 0 1) surface. The LEED and AFM observations revealed that the In film surface on the vicinal Si(0 0 I) consists of 3 x 4 terraces and (3 1 0) facets. The area ratio of the facet to the terrace exhibited abrupt an increase at T-c. It is believed that the change of the mass transport is related to the abrupt change of the area ratio of the facet to the terrace. Both the critical temperature T-c and the spread due to the surface electromigration of the In film depended on the configuration of the DC current direction and the step edge.