There is provided an image forming system that automatically discharges paper sheets other than poorly fed ones without making an emergency stop, even when poor paper feeding is caused due to a paper jam or the like. At paper feeding, information showing poor paper feeding is transmitted when the poor paper feeding is detected in supplying the paper sheets. At image forming, a determination is made whether the paper conveyance in forming the image is continued or stopped when an instruction, based on the information showing the poor paper feeding. At paper discharging, a determination is made whether the paper conveyance in discharging the paper sheets is continued or stopped when an instruction, based on the information showing the defective conveyance.