PURPOSE: To always place a surface material in a proper position on a frame, by installing a cylinder having a guide for moving the surface material in the direction of its width and another cylinder having a moving end for supporting the surface material and by orienting both the cylinders oppositely to each other.
CONSTITUTION: A cylinder 7 having a guide 6 for moving a surface material in the direction of its width and another cylinder 9 having a moving end 8 for supporting the surface material are installed so that both the cylinders are oriented oppositely to each other. The upper part of the guide 6 is perpendicularly bent forward. The guide 6 is located on the moving end of the cylinder 7, which is caused to move back and forth almost horizontally. The moving end 8 of the cylinder 9 is caused to move back and forth horizontally. The guide 6 is moved forth in the direction of an arrow while one side edge of the surface material 1 is supported by the moving end 8 on a frame 4. The surface material 1 is thus placed in a proper position on the frame 4. Such a positioning device can be applied to assemble building wall panels or the like.