A rolling mill has upper and lower work rolls brought into contact with a material to be rolled. An upper backup roll supports the upper work roll, and a hydraulic jack above the upper backup roll adds a pressurizing load adjusted in accordance with a rolling load to the upper work roll via the upper backup roll. The hydraulic jack includes a cylinder arranged such that its bore faces downward and contains therein a slidable ram. A thrust metal block is disposed on an upper surface of the cylinder in a manner which allows it to move between a first position for the rolling work and a second position for exchanging the rolls, the second portion being spaced apart from the first position in an axial direction of the upper backup roll. A pressurizing screw is arranged to abut on an upper surface of the thrust metal when the thrust metal is at the first position, so as to restrict an upward movement of the thrust metal and thereby determine a position of the upper work roll. Further, an actuator is mounted on the cylinder and operatively connected to the thrust metal for moving the thrust metal between the first position and the second position.