To provide a plate material conveying device with which the elevation of a plate material conveying speed and the shortening of its accelerating/decelerating time are possible and the conveyance efficiency of small plate materials can be improved by making travelling members compact and the plate material can be conveyed by properly using a suction type plate material holder and a gripper.

Travelling members 13, 14 are provided on tracks 11, 12 freely travellably. Each travelling member 13, 14 has a plate material holder supporting frame 21, 22 for supporting the suction type plate material holders 23A, 23B, 23C. The plate material holder support frames 21, 22 have frame main bodies 21a, 22a and turnable frames 21b, 22b which is freely turnable to a position where the plate material supported approximately horizontally so as to be freely turnable with respect to the frame main bodies 21a, 22a is superposed on the adjacent track planarly. Each turnable frame 21b, 22b has a gripper 60 for gripping an end of the plate material. The opening of the gripper 60 is able to face the middle side of the plate material.