An image bearing member on which an electrostatic image is to be formed; a rotatable supporting member, configured to support a developing device for developing the electrostatic image and configured to rotationally move the developing device toward a developing position, provided movably in a rotational axis direction with respect to a main assembly of the image forming apparatus; an urging member for urging the rotatable supporting member in the rotational axis direction; and a regulating portion for regulating a position of the rotatable supporting member, with respect to the rotational axis direction, urged by the urging member are provided.