PURPOSE: To enable a tool gap to be promptly adjusted accurately and automatically by a remote control by giving a preload to a thrust bearing and driving a hydraulic cylinder, formed in the periphery of the thrust bearing, by a hydraulic mechanism.

CONSTITUTION: When a machine adjusts its tool gap, the machine, stopping upper and bottom drum shafts 3a, 3b so as to oppose their tools by rotating a motor in a fine speed and inching a solenoid valve MV-2 in a low pressure line reducing the pressure, measures a position of the bottom drum by a differential transformer 21, when a rise up part of the pressure of oil is recognized, by the display of a control disc 29 through a pressure switch 25 or the like, and when the zero point is stored in memory in a computer 28, the machine, controlling the MV-2 by the disc 29 in accordance with a plate thickness because the zero point is electrically stored in memory, enables the gap to be adjusted accurately and promptly further fully automatically by a remote control.