PURPOSE: To provide the plate forming device which can execute an adjusting operation of a supporting position after a plate is subjected to clamp operation, and also, can obviate a warp by moving a coordinate of a forming metallic fixture even if the warp exists in the supporting position.

CONSTITUTION: In the plate forming device of a vertical type in which the surface and the reverse side of a plate W are supported in an erect attitude and the above plate W is supported by a plate supporting device 1 so as to be movable horizontally along the above surface and reverse side, and forming metallic fixtures 9, 11 are placed on both sides of the above surface and reverse side, respectively, the plate supporting device 1 is provided with plural supporting implements 7 constituted so as to be movable in the direction being parallel to the above surface and the reverse side by supporting the end part of the plate W.