The present invention relates to an image forming apparatus to which a process cartridge can be detachably attached, comprising: a housing body to which the process cartridge is attached; an opening and closing portion for detachably attaching the process cartridge; and securing means for securing the process cartridge to a position where an image can be formed. The securing means is turned when the process cartridge is detached and attached, the image forming apparatus further comprises force-applying means which applies a force to the process cartridge to a position where the process cartridge is secured or a position where the process cartridge is opened, and an image is not formed when the securing means is in a phase other than a process cartridge securing phase.