Method for evaluating an electrical property of a transfer device

A transfer device (29) including a combination which includes an intermediate transfer medium (10) ; and at least one transfer member (62; 16) configured to transfer a toner image while contacting a backside of the intermediate transfer medium and applying a transfer bias thereto, wherein the combination has a property such that when the combination is repeatedly subjected to charging and discharging, in which a voltage of absolute value of 1 kV is applied for 60 seconds, and then discharging is performed for 10 seconds, 300 times while measuring a combined volume resistivity of the combination, an absolute value of logarithmic difference between a first combined volume resistivity and a 300 th combined volume resistivity is not greater than 0.8 [log (© · cm)].