In a forming apparatus, inner frames are arranged in a forming roll stand so as to move up and down. Mechanical structures of convexo-concave engagement are provided on opposed faces between respective roll chocks and yokes and the inner frames. After connection with a pressing device is released, the roll chocks and yokes are guided utilizing the moving-downward motion of the inner frames, and a stack body is formed in series so as to be withdrawn from the roll stand. The stack body is disassembled utilizing the moving-upward motion of the inner frames, and the roll chocks and yokes can be guided to the desired positions inside the stand and locked.