are arranged around the first downstream side intermediate transfer roll 20 b from the upstream side to the downstream side with respect to the rotating direction of the first downstream side intermediate transfer roll 20 b further regarding the arrangement of the members around the second intermediate transfer roll 30 the first upstream side intermediate transfer roll 20 a the first downstream side intermediate transfer roll 20 b the toner sensor 8 the final transfer roll 40 the cleaning roll 310 and the brush roll 313 are arranged around the second intermediate transfer roll 30 from the upstream side to the downstream side with respect to the rotating direction of the second intermediate transfer roll 30 each of the first intermediate transfer rolls 20 a and 20 b is formed by providing a silicone rubber layer on a metal pipe and forming thereon a high release coating layer while the acceptable resistance value thereof normally ranges from 10 5 to 10 9 u03c9 in this example it is approximately 10 8 u03c9 this electrical resistance value is higher than that of the cleaning rolls 210 a 210 b and 310 and the requisite surface potential for transferring toner images from the photosensitive drums 10 y through 10 k to the first intermediate transfer rolls 20 a and 20 b normally ranges from approximately 250 through 500 v and an optimum potential value can be set according to the toner charging condition the ambient temperature the humidity etc like the first intermediate transfer rolls 20 a and 20 b.