An electrophotographic image forming apparatus includes an electrophotographic image forming apparatus main assembly including a preventing portion; a supporting member for supporting a plurality of electrophotographic photosensitive members, the supporting member being movable between an inside position inside the main assembly and an outside position outside the main assembly in a state in which the supporting member is supported by the main assembly and being disengageable from the main assembly at the outside position; a handle portion, provided to the supporting member, to be touched for disengaging the supporting member from the main assembly; and a portion to be prevented, provided to the supporting member, being movable between a preventing position in which the portion to be prevented contacts the preventing portion in order to prevent the supporting member from being disengaged from the main assembly and a retracted position in which the portion to be prevented is retracted from the preventing position in order to disengaging the supporting member from the main assembly. The portion to be prevented is moved from the preventing position to the retracted position by the touch of the handle portion.