PURPOSE: To press a resin plate uniformly without imposition of an excessive load on a balanced supporting device by arranging the balanced supporting device at the bed of a press and carrying out a follow-up control of a slide close to the balanced supporting device.

CONSTITUTION: A pressure cylinder 3 is driven by a servo pump 19 to cause a slide 4 to descend at high speed. Then the slide slows down at a location slightly upward where a resin plate 9 is pressed, and is mounted at the balanced supporting device 8. The device 8 descends according to a program and fills resin plate 9 in the liquid phase into a cavity 21 formed by top force 10 and a bottom force 11. If the supporting force of the device 8 is reduced beyond the reference level by the resistance of the resin plate 9, the discharge of the servo pump 19 is increased, thus increasing the descending speed of the slide 4. If the pressure of the slide 4 is increased, thus providing a larger supporting force than the reference level, the discharge of the pump 19 is lessened to slow the descending speed of the slide 4 and always cause the slide 4 to follow up closely on the balanced supporting device 8.