Oscillating transport unit for post-processing device

An image forming system provided with a post-processing section for conducting a post-processing of a sheet, the image forming system comprising:

• an image forming section for forming an image on the sheet, such that the sheet is an image-recorded sheet;
• a plurality of post-processing sections arranged at vertically different positions with each other;
• a transporting unit adjustable of the transporting plane angle so that the image-recorded sheet is possible to be delivered and received between the plurality of post-processing positions;
• and
• an oscillating mechanism for oscillating the transporting unit to change a transporting plane angle of the transporting unit;
• wherein, the oscillating mechanism oscillates the transporting unit to arrange different from each other, a first transporting plane angle at the time when the transporting unit receives the booklet from the first post-processing section provided at a higher position, a second transporting plane angle at the time when the transporting unit conveys the image-recorded sheet to a second post-processing section positioned at a lower position, and a third transporting plane angle at the time when the transporting unit carries out the image-recorded sheet processed by the second post-processing section.