PURPOSE: To eliminate the uneven cooling in the transverse direction of a steel plate by constituting specifically an upper hollow guide roll of a steel plate cooler using cooling water so that the cooling water after cooling is discharged by said roll.

CONSTITUTION: Water inflow holes 13 are arrayed at every specified interval on the surface of a cell 12 rotating around the shaft 11 of an upper hollow guide roll 10 of a cooler. Key-shaped paddling plates 14 are disposed near the same and water outflow holes 15 are disposed on the end face of the roll near the root part of said plates. Then the cooling water 3 flowing on a steel plate 1 in the arrow-marked advance direction of said plate advances through the holes 13 located on the bottom surface of the cell 12 into the hollow part. The water 3 is scraped by the plates 14 according to the rotation of the roll and is lifted in the rotating direction of the roll. While the roll performs about 1/4 turn, the water flows axially in the roll and is discharged through the holes 15 at the end of the roll to the outside of the device. Thus the water flowing on the plate 1 runs only in the advance direction of the plate 1 and after cooling the plate 1, the water enters the roll, from which the water is discharged. The water flow in the transverse direction of the plate is eliminated and the uneven cooling in the transverse direction of the plate is eliminated.