In accordance with the state of a document tray upon powering on a power source, the elevation operation of a document tray is controlled. In the case that the document tray is located not at the highest position, not at the lowest position, but at a middle position upon powering on the power source, the document tray is allowed to remain at the middle position as it is without performing the elevation of the document tray. In the case that the document tray is located at the highest position, the document tray is moved down. By reducing the wasteful operation (the initial operation) after powering on the power source, it is possible to reduce the operation time and the efficient sheet processing can be realized.