By connecting a first diode between a conductive heating element of a fixing roller and ground, electric charge with the same polarity as the charged polarity of toner can be held on the surface of the fixing roller. Meanwhile, by connecting a second diode between the surface of a pressing roller that does not contact an un-fixed toner image and ground, electric charge with the reverse polarity of the charged polarity of the toner can be held at the surface of the pressing roller. The polarity of the electric charge induced by electromagnetic induction is held at the polarity determined by the two diodes, and as a result the fixing offset can be suppressed without adding a collector member or a charging capacitor.