The dc self-bias voltage of RF planar magnetron discharges of argon gas was clarified by performing particle-in-cell/Monte Carlo (PIC/MC) simulations. The self-bias increased with increasing magnetic field and became positive. This dependence of self-bias on the magnetic field agrees with the experimental result, the theoretical result, and the numerical result of fluid simulation on magnetically enhanced capacitively coupled plasma with a magnetic field parallel to the electrode surface. The plasma was confined between the magnetic poles for a narrow gap (30 mm), but spread over a large space for a larger gap. (c) 2005 Elsevier B.V. All rights reserved.