PURPOSE: To optimize the shape of the dog bone to be generated to a hot slab and to prevent the spread during horizontal rolling in the succeeding stage in the stage of subjecting the hot slab to cross rolling down and pressing with a pair of upper and lower anvils by providing relief slopes to the inlet and outlet side of the upper and lower anvils and subjecting the surfaces of the anvils to a surface roughening treatment.

CONSTITUTION: While the hot slab 1 is fed between the upper and lower anvils 2 and 2, the slab is repeatedly grasped under pressure in the transverse direction, by which the slab 1 is cross rolled down. The slopes 4, 4 are provided to the slab inlet side in the parallel parts 3 of the anvils and the slopes 5, 5 are provided to the outlet side. Grooves 7 along the conveying direction of the slab 1 are formed on the rolling down surfaces of the anvils 2. The frictional force between the anvils and the slab is increased by the grooves 7, by which the thickness increase component in the side parts of the slab is decreased. The thickness increase regions of the slab move particularly toward the center of the slab width and therefore the spread in the horizontal rolling succession to the cross rolling is kept small and therefore the cross rolling down efficiency is improved.