A four high mill of a paired-roll-crossing type comprises upper and lower equalizer beams held in contact, respectively, with the uppermost and lowermost surfaces of upper and lower backup roll bearing cases and made movable upwardly and downwardly within a housing, roll-crossing devices mounted in the housing to turn the bearing cases that contain upper and lower work chocks about a common vertical axis on the same horizontal plane so that upper and lower pairs of rolls can cross each other, and devices for separately setting the left and right roll gaps between upper and lower work rolls. The mill further comprises work roll-bending devices mounted at both ends of the work rolls.