An image forming apparatus of the present invention includes a plurality of components that form image forming means and should be mounted or dismounted in a preselected order. Following one of the components with respect to the preselected order cannot be dismounted from the apparatus until preceding one of the same has been dismounted. The components are mounted to the apparatus in the reverse order. The components unremovable from the apparatus and positioned above the removable components in a preselected dismounting direction are retractable.