An image forming apparatus (100) includes a discharge section (210), a paper receiving tray (93), a first detecting section (211), a lever (220), a second detecting section (230) and a decision section (240). The first detecting section (211) is disposed in the discharge section (210), and detects a paper jam. The second detecting section (230) detects a swinging state of the lever (220) from a first position at which the lever (220) is not in the process of receiving an action of the paper sheet to a second position. The decision section (240) judges an occurrence factor in a paper jam to be a user-induced factor when the second detecting section (230) detects a state in which the lever is at the first position in a state where the first detecting section (211) detects the paper jam. Also, the decision section (240) judges the occurrence factor in the paper jam to be an image forming apparatus-induced factor when the second detecting section (230) detects a state in which the lever is swung over the first position in the state where the first detecting section detects the paper jam.