Embodiments of the invention provide a head which can prevent an external magnetic field form erasing a signal on the medium and whose main magnetic pole piece does not corrode during processing of the air bearing surface. In one embodiment, an anti-corrosion electrode is formed to apply a voltage to the main magnetic pole piece during processing of the air bearing surface. This retards corrosion of the main magnetic pole piece. Since a conductor (anti-corrosion wire) connected to this anti-corrosion electrode is made of a nonmagnetic material, concentration of an external magnetic field into the main magnetic pole piece can be suppressed. Consequently, since the magnetic leakage field emitted from the main magnetic pole piece is reduced, erasure of the signal on the medium can be prevented. In addition, since the anti-corrosion wire is connected to the upper core, this wire can be formed in the same wiring layer as a wire which connects the coil to a write terminal, resulting in a simplified manufacturing process.