Image forming apparatus and paper-jam clearing method

A paper conveying path extends from a paper feeding tray to an image forming unit, a branch conveying path extends from a branching point in the paper conveying path to a paper container, a first paper sensor and a second paper sensor are arranged in the paper conveying path upstream of the branching point, and a switch nail is arranged at the branching point to switch paths between the paper conveying path and the branch conveying path. The switch nail is controlled so that a jammed paper is conveyed to the paper container via the branch conveying path upon detecting paper jamming in the paper conveying path and the first sensor detects the jammed paper while the second sensor does not detect the jammed paper.