Relay conveyance device

A relay conveyance device comprising:

• a relay conveyance path being arranged between an image forming apparatus forming an image on a sheet and a post processing device carrying out post process to the sheet with the image formed by the image forming apparatus to convey the sheet from the image forming apparatus to the post processing device;
• at least two reversing units reversing a surface side and a back-face side of the sheet;
• and
• a control device controlling conveyance of the sheet on the relay conveyance path,
• wherein the relay conveyance path includes:
• at least two reverse paths respectively passing through the at least two reversing units;
• a branch section branching into the at least two reverse paths at an upstream side;
• and
• a confluence section joining the at least two reverse paths,
• the control device controls the branch section and the confluence section to convey the sheet while alternately switching the at least two reverse paths, measures an interval time between the sheets passing through the confluence section, and controls conveyance of the sheet in the at least two reverse paths so as to uniformize the interval time.