Patent ID: 8608150

Claim:
A sheet post-processing apparatus comprising: a first post-processing portion that collects sheets delivered from an image forming apparatus and performs first post-processing; a second post-processing portion that performs second post-processing on the sheets delivered from the image forming apparatus; an entrance through which the sheets delivered image forming apparatus are brought in; a first delivery path that guides the sheet delivered through the entrance to the first post-processing portion; a sheet holding path having a first holding path which branches off from a branch point of the first delivery path and a second holding path which is formed to be continuous with the first holding path and joins together with the first delivery path, the sheet holding path allowing the sheet delivered to the first post-processing portion to be held at the first holding path and the second holding path; a second delivery path that branches off from a branch point of the first holding path and guides the sheet delivered to the first holding path to the second post-processing portion; a buffer roller disposed proximity to the entrance, an upper end of the buffer roller being close to a lower portion of the first delivery path, and the first holding path and the second holding path being disposed along an external circumference of the buffer roller; a first path switching portion that is provided at the branch point of the first delivery path and selectively switches to connect the first delivery path to the first holding path or the first delivery path on a side of the first post-processing portion; and a second path switching portion that is provided at the branch point of the first holding path and selectively switches to connect the first holding path to the second holding path or the second delivery path.