An image forming apparatus, comprising: an image forming section adapted to form an image onto a paper sheet; a conveyance section adapted to convey the paper sheet; an ejecting section adapted to eject the paper sheet onto an ejecting tray; an abnormality detecting section adapted to detect a primary abnormal state in which the conveyance section is incapable of continuing an operation convey the paper sheet, and a secondary abnormal state in which a certain influence is possibly incurred to the image formed on the paper sheet though the conveyance section is capable of continuing the operation to convey the paper sheet; and a control section adapted to conduct controlling operations to convey the paper sheet in accordance with an image forming operation performed by the image forming section, so as to eject the paper sheet onto the ejecting tray of the ejecting section; wherein, when the abnormality detecting section detects the primary abnormal state and the abnormality detecting section detects the secondary abnormal state in midcourse of the operation to convey the paper sheet, the paper sheet, detected as in the primary abnormal state and in the secondary abnormal state, is defined as a jam-causing paper sheet, and the control section is further adapted to control the conveyance section to halt the operation to convey the jam-causing paper sheet; and wherein the control section is further adapted to control both the conveyance section and the ejecting section to implement a pre-purge processing to convey a jam-subsequent paper sheet, remaining upstream from the jam-causing paper sheet, so as to eject the jam-subsequent paper sheet onto the ejecting tray; and wherein, in a case where the secondary abnormal state in respect to the jam-subsequent paper sheet is detected by the abnormality detecting section in midcourse of performing the pre-purge processing thereof, the control section is further adapted to control the conveyance section to continue the operation to convey the jam-subsequent paper sheet without halting the operation to convey the jam-subsequent paper sheet. an image forming section adapted to form an image onto a paper sheet; a conveyance section adapted to convey the paper sheet; an ejecting section adapted to eject the paper sheet onto an ejecting tray; an abnormality detecting section adapted to detect a primary abnormal state in which the conveyance section is incapable of continuing an operation convey the paper sheet, and a secondary abnormal state in which a certain influence is possibly incurred to the image formed on the paper sheet though the conveyance section is capable of continuing the operation to convey the paper sheet; and a control section adapted to conduct controlling operations to convey the paper sheet in accordance with an image forming operation performed by the image forming section, so as to eject the paper sheet onto the ejecting tray of the ejecting section; wherein, when the abnormality detecting section detects the primary abnormal state and the abnormality detecting section detects the secondary abnormal state in midcourse of the operation to convey the paper sheet, the paper sheet, detected as in the primary abnormal state and in the secondary abnormal state, is defined as a jam-causing paper sheet, and the control section is further adapted to control the conveyance section to halt the operation to convey the jam-causing paper sheet; and wherein the control section is further adapted to control both the conveyance section and the ejecting section to implement a pre-purge processing to convey a jam-subsequent paper sheet, remaining upstream from the jam-causing paper sheet, so as to eject the jam-subsequent paper sheet onto the ejecting tray; and wherein, in a case where the secondary abnormal state in respect to the jam-subsequent paper sheet is detected by the abnormality detecting section in midcourse of performing the pre-purge processing thereof, the control section is further adapted to control the conveyance section to continue the operation to convey the jam-subsequent paper sheet without halting the operation to convey the jam-subsequent paper sheet.