Abstract: An image forming apparatus includes a photosensitive member on which an electrostatic latent image is formed. The electrostatic latent image is developed by toner and the toner image thus developed is transferred on a copying paper. A stopper is provided in the path of the copying paper to a transferring station. A first paper path for manually feeding paper, and a second paper path is provided for automatically feeding paper. The first and second paths join each other at an upstream side of the stopper. Downstream of the junction of the two paths is formed a common path in which the stopper is disposed. In the common path at the upstream side of the stopper, there is arranged a sensor for sensing the presence of copying paper. In an automatic feeding mode, when a signal is not given from the sensor within a predetermined period of time after a paper feed roller is operated, the occurrence of a jam will be detected.