The step structure transition between a regular step and a bunched step on vicinal SiO(111) surfaces induced by DC is studied by the kinetic Monte Carlo simulation in a terrace-adatom-step-kink (TASK) model. In the TASK model, effective force due to DC is taken into account explicitly on the mass transport of Si adatoms. In the diffusion-limited regime corresponding to the experimental temperature range Pi, step bunching is induced by step-up force and in-phase wandering of a regular step is formed by step-down force. The in-phase wandering of a regular step is formed by nucleation growth mode and the amplitude of wandering grows with time in proportion to roott. The period of in-phase wandering decreases as the effective force increases, consistent with the recent experimental results. (C) 2002 Elsevier Science B.V. All rights reserved.