A guide unit 24 includes an electrically conducting guide plate 25 disposed upstream of the transfer unit 20 that transports toner image transfer sheets between the image carrier 7 and the transfer unit 20, an electrically insulating support member 26 that supports the guide plate 25, an electrically conducting connecting member 30 installed on the support member 26, electrically connected to a ground plate 33, and a non-linear element 31 directly or indirectly electrically connected between the guide plate 25 and the connecting member 30. Further, if a voltage equal to or greater than a predetermined value is applied between the guide plate 25 and the connecting member 30, the resistance value is reduced.