To increase consistency of stacked paper by a means for positioning the end of a paper in a specified position by moving a means for regulating the end of the carried paper in a direction parallel to a paper regulating direction and a means for vibrating the regulating means positioned in a specified location.

First, the size of paper is recognized (ST1), and a side guide is moved and fixed matching the end of a direction vertical to the carrying direction of the paper (ST2). Then, an end guide is moved according to the size of the paper in a carrying direction and fixed (ST3). After this operation is finished, a carrier roller is rotated (ST4), and then a side guide vibrating mechanism starts its operation (ST5). Further, the operation of the carrier roller is finished (ST7), then the operation of the side guide vibrating mechanism is finished (ST8), and a stacking operation is completed. Thus, without vibrating the side guide itself in a middle tray by a number of times, paper is stacked without stopping carried paper.