lower frame 7 the set plate 10 is constituted by a plate 30 mounted to the lower frame 7 and a pin 32 fixed to a side of the upper frame 6 the plate 30 is formed with a long hole 31 with which the pin 32 is engaged and the upper frame 6 and the lower frame 7 are integrated movably in the up and down direction by a movable amount h by the above described constitution the movable vacuum forming apparatus x can be handled integrally as a single body as described above the hermetically sealed space r at inside of the movable vacuum forming apparatus x is brought into a vacuum state and at that occasion strain may be caused at the interpenetrated portion 11 in an inner side direction by the atmospheric pressure particularly when the movable vacuum forming apparatus x is in the quadrangular shape the strain is enlarged at a vicinity of a central portion of a side of a straight line there is a danger of constituting sealing failure by opening a clearance between the interpenetrated portion 11 and the upper frame 6 by the strain of the interpenetrated portion 11 therefore according to the invention the packing 22 is provided with a function of compensating for the strain that is as shown by fig3 the packing 22 in the ring like shape is constituted by a main body 23 in a ring like shape and a lip 24 in a ring like shape the main body 23 is fitted to.