PROBLEM TO BE SOLVED: To obtain a high-quality printed result even when the thickness of a record medium is changed and to prolong the exchanging cycle of a cleaning member with respect to an electrophotographic device. SOLUTION: This electrophotographic device is provided with a transfer roller 7 transferring a toner image formed on an image carrier 1 on the record medium (p), a thickness detection sensor 16 detecting the thickness of the medium (p), a voltage controller 10 controlling transfer voltage applied to the roller 7 based on the thickness of the medium (p) detected by the sensor 16 and a fixing roller 18 and a pressure roller 10 fixing the toner image transferred on the medium (p). Besides, a fixing voltage control means controlling fixing voltage applied between the rollers 18 and 20 based on the thickness of the medium (p) detected by the sensor 16 is arranged in the controller 10.