A method for evaluating an electric resistance member of an image forming apparatus which can maintain good image quality, without the occurrence of transfer defects such as insufficient transfer, even in a long-term use. An intermediate transfer belt of the image forming apparatus, which is evaluated based on a fluctuation characteristic of the resistivity in a period of continuous voltage application, is used. The absolute value Δρs of the amount of changes in the surface resistivity of the intermediate transfer belt within 2 seconds to 100 seconds from the beginning of voltage application is 0.3 [Log(Ω/)] or less, when the surface resistivity ρs is measured by applying a voltage of 500 V. The absolute value Δρv of the amount of changes in the volume resistivity within 2 seconds to 100 seconds from the beginning of voltage application is 0.5 [Log(Ω·cm)] or less, when the volume resistivity ρv is measured by applying a voltage of 200 V.