To provide a collating device with a simple transferring of paper capable of being installed even on a narrow place.

The collating device has a horizontal carrying part 5 whose one part is disposed under an image forming means, a vertical carrying part 2, a paper receiving part 3 for finishing of image forming disposed between the vertical carrying part and the image forming means, a plurality of paper loading trays 7 movable at a tray disposition part 6 on the horizontal carrying part, a paper transfer means 40 which is provided on the receiving part 3 and drop-transfers the paper on the paper loading trays 7 below, and a collation paper feeding part 80 which is provided at a collation position C of the tray disposition part 6 and feeds the paper to the horizontal carrying part. The image forming finished paper enters the receiving part 3, it drops on the trays 7 at the immediately below to be loaded, and afterward, moves to the collation position C, fed out to the horizontal carrying part, and the collation is performed.