Image forming device with first and second transfer power sources

An image forming device comprising:

• a thin-walled image carrier that movably carries an image formed by charged imaging particles;
• a transfer device that includes paired transfer members that sandwich and transport the image carrier and a recording medium, and transfers the image carried on the image carrier in a transfer region sandwiched by the paired transfer members;
• a guide member, provided in a grounded state farther upstream in a transport direction of the recording medium than the transfer region of the transfer device, that guides the recording medium to the transfer region;
• and
• a transfer power source that causes a transfer electric field to act in the transfer region by imparting a transfer voltage between the paired transfer members, wherein
• the transfer power source includes
• a first transfer power source that imparts a first transfer voltage used normally to either one of the paired transfer members, and
• a second transfer power source that activates together with the first transfer power source when the recording medium has a predetermined resistance value or less, or is of low resistance having a conductive layer along a medium substrate face, the second transfer power source imparting a second transfer voltage of opposite polarity from the first transfer voltage and having an absolute value that is less than or equal to the first transfer voltage to the other of the paired transfer members.