Effects of horizontal magnetic field paralleling to the iron electrodes with various configurations on the anodic behavior in sulfuric acid solution are investigated. The magnetic field effect is stronger for the horizontally placed upward electrode than for the horizontally placed downward and the vertically placed electrodes. Locally dissolution-mitigated regions are found at two ends of the electrode along the direction perpendicular to the magnetic field direction in addition to the locally accelerated dissolution region at two ends paralleling to the magnetic field direction. The effect of magnetic field on convection process is critical in determining the anodic current density.