An image forming apparatus is provided. In the image forming apparatus, a contact portion that contacts a detection gear of a development cartridge and to which information about the development cartridge is transmitted is positioned inside of a path for attachment and detachment of a process cartridge. At both times of attachment and detachment of the process cartridge to and from a main unit casing, when the process cartridge contacts the contact portion, the contact portion can be swayed in a single direction while a pivot extending in a direction parallel to the direction of attachment and detachment of the process cartridge is taken as a fulcrum for swaying action.