PURPOSE: To stack plate materials precisely by supportingly conveying them with a pair of the right and left conveyors, allowing them to hit a stopper material, and making the conveyor distance variable with air cylinders in an automatic stacker of plywood.

CONSTITUTION: The distance between vertical rollers 28, 29 is made consistent with the width of a plate material via the rotation of a manual handle 34 and screw shafts 24, 25; the plate material is conveyed while air cylinders 36, 37 and side end and front end positioning air cylinder 31, 43 are contracted; then rotors 18, 19 are rotated by motors 22, 23 of the right and left conveyors 14, 14; and the plate material is conveyed until it hits a stopper material 39. When it hits the stopper material 39, the motors 22, 23 are stopped, the air cylinders 36, 37 are extended to increase the distance between the right and left conveyors 14, 15. Accordingly, the plate material loses the hook of the rollers 18, 19 on both sides and is dropped on a lifter located directly beneath it keeping its attitude under conveyance. At this time, the side end and front end positioning air cylinders 31, 43 are extended and precisely align the plate materials together with the stopper material 39.