Electrophotographic belt and electrophotographic image forming apparatus

An electrophotographic image forming apparatus comprising an electrophotographic belt as an intermediate transfer belt, wherein

• the electrophotographic belt comprises a biaxially stretched cylindrical film as a base layer,
• the biaxially stretched cylindrical film comprises crystalline polyester, amorphous polyester and carbon black,
• a content of the carbon black with respect to the biaxially stretched cylindrical film is 2.0% by mass or more, and
• a surface resistivity measured on the surface of the biaxially stretched cylindrical film in an environment of a temperature of 23° C. and a relative humidity of 50% is 1×103 Ω/square or higher and 1×1013 Ω/square or lower, and
• A/B is 3.00 or smaller, where A (Q/square) represents a surface resistivity measured on the surface of the biaxially stretched cylindrical film after the biaxially stretched cylindrical film is left to stand for 24 hours in an environment of a temperature of 23° C. and a relative humidity of 50%, and B (Ω/square) represents a surface resistivity measured on the surface of the biaxially stretched cylindrical film after the biaxially stretched cylindrical film is left to stand for 24 hours in an environment of a temperature of 30° C. and a relative humidity of 80%.