To ensure a resistance which nearly does not tend to depend on environmental changes, such as a temperature or humidity change as well as to make the intrasurface resistance of an electrically conductive belt stabilized by using a high molecular polymer composition containing an antistatic agent having boron atoms.

This electrically conductive belt 6 comprises a high molecular polymer composition, containing an antistatic agent having boron atoms. When a 300 V voltage is applied repeatedly 200 times to the belt 6 for 10 sec each, while suspending application for 3 sec, the initial volume resistance R1 of the belt and the volume resistance R2 after the repeated application have a relation 0≤LogR2-LogR1≤1.5. When Log(R2/R1)<1.5, an image becomes stabilized, the dependency of resistance on an environmental change lowers and the image is hardly affected by the ambient temperature and humidity. The relation between the volume resistance Rs at 23°C and 50% relative humidity and the volume resistance Rh at 30°C and 90% relative humidity preferably satisfies the expression 0≤LogRs-LogRh≤2.