Patent ID: 7580646

Claim:
An image forming apparatus comprising: a sheet feeding device that feeds a transfer material; a receiving device that receives image data; an image forming device that forms an image on a first side and a second side of the fed transfer material based on the image data received by said receiving device; an inversion device that feeds the transfer material having the image formed on the first side thereof until the transfer material is partly exposed to outside of the image forming apparatus and then feeds the transfer material to a refeeding path in the image forming apparatus for image formation on the second side of the transfer material; a pullout detecting device that detects whether or not the transfer material is pulled out before the feeding of the transfer material by said inversion device is completed, and detects a degree of pulling out of the transfer material; and a warning device that warns of the pulling out of the transfer material when the pulling out of the transfer material is detected by said pullout detecting device, wherein said warning device changes type of the warning according to the detected degree.