Transfer device, image forming apparatus and method for evaluating electric property

th th A transfer device including a first combination including an intermediate transfer medium and a transfer member applying a transfer bias, and/or a second combination including an intermediate transfer medium, a second transfer member applying a second transfer bias, and an opposing member configured to transfer the toner image on the intermediate transfer medium to a receiving material at a second transfer nip. When the first combination is subjected to 60-second application of a voltage of 1 kV, followed by discharging, 300 times, the absolute value of logarithmic difference between first and 300combined volume resistances is not greater than 0.8 [log(Ω)]. When the second combination is subjected to 60-second application of a voltage of −1 kV, followed by discharging, 300 times, the absolute value of logarithmic difference between the first and 300combined volume resistances is not greater than 0.5 [log(Ω)].