PURPOSE: To prevent stacked sheets from being stained by images formed on other sheets by installing a means for controlling a reversal means so that the sheets are stacked on a placing means, by opposing the surfaces on which images are formed.

CONSTITUTION: The sheets having the order of odd number P1, P3, P5,... among the sheets each of which is transported one by one from a sheet bundle 106 and has an image formed on one side are introduced into a passage (a) by a flapper 110, and sent in the state where the image surface is directed down ward into an intermediate tray 111. Further, the sheets in the order of even number P2, P4, P6... are introduced into a passage (b) by the flapper 110, and after the rear edge passes through a branch point between the passage (b) and a passage (d), the flapper 110a is switched, and the sheet is sent in the reverse direction by revolving a pair of transport rollers 117 in the reverse direction. The rear edge of the sheet is introduced into the passage (d) by the flapper 110a, and sent into the intermediate tray 111, setting the image surface upward.