An electrophotographic photosensitive drum usable with an electrophotographic image forming apparatus, includes a non-circular twisted projection provided at one longitudinal end of the drum, and engageable with a non-circular twisted hole being disposed at a central portion of a driving rotatable member of a main assembly of the image forming apparatus, and an electroconductive member provided on the projection, electrically connected to the drum, and contactable with an electroconductive member electrically connected with a main assembly of the image forming apparatus and disposed in the hole to ground the drum. The contact position between the electroconductive members moves in interrelation with the projection being moved toward the hole by rotation of the driving rotatable member when the projection is engaged with the hole.