A control system of a machine tool includes a hydraulic pressure adjuster. The hydraulic pressure adjuster includes a sequence program controller that includes components for adding a function of adjusting a hydrostatic pressure of a static pressure oil supplied to a hydrostatic pressure guide mechanism, which are a pressure setting unit, a constant acceleration motion controller, a workpiece-weight calculator and a supply state adjuster.

An air balance mechanism includes a plate part, fixed shafts, and movable cylinders. A flange is provided at one end of each of the fixed shafts. The movable cylinders are movable relative to the fixed shafts. A space is formed below a lower surface of the flange. Further, the air balance mechanism includes fixing bolts and adjusting bolts. The fixing bolts fix the flange and a plate part at positions different from the space. The adjusting bolts are inserted into the plate part through the space for allowing the postures of the fixed shafts to be adjustable.

A table group for a machine tool is provided. The table group has a support assembly, a table, a ring gear provided with a lower face and an upper face, integral with the table, a plurality of main hydrostatic skids, a detection device for detecting a lifting action generated by the main hydrostatic skids, a plurality of dogs and an electronic management device operatively connected to the main hydrostatic skids, the dogs and the detection device, configured to control the dogs to generate a contrasting action. The lifting action is equal to a predetermined constant nominal load greater than the weight of a semi-finished product and either smaller than or equal to a maximum load which can be borne by the main hydrostatic skids.