An image forming apparatus includes: a casing; a developer having a plurality of developers and a rotational body that is rotatably supported on the casing, the plurality of developers being able to be mounted with a toner replenishment container filled with toner, and being disposed on a peripheral surface of the rotational body; a replacement door that opens the replacement hole when opened and closes the replacement hole when closed; and a pressing portion that presses the toner replenishment container that is inserted into the replacement hole into a mounting position of the developer under interlocking with a closing operation of the replacement door and mounts the toner replenishment container to the mounting position of the developer, and is fastened to the casing after mounting in a state apart from the rotation type developer.