To improve yield by enabling the remarkable reduction in the amount of width drop in the tip part and/or the tail end of a hot slab.

In this method, the preform of the tip is executed by edging the tip of the slab 2 using the inlet-side inclined part 3a of a pair 1 of anvils which are widened in the opposite direction to the advancing direction of the hot slab 2 and, after that, the edging of the hot slab 2 with the inlet-side inclined part 3a and parallel part 4 is successively executed. Next, at the point of time where the edging of the hot slab 2 with the parallel part 4 of a pair 1 of the anvils reaches a prescribed position on the side of the tail end of the slab 2, a pair 1 of the anvils is once opened and, after executing empty-feeding of the slab 2, the preform of the tail end is executed by edging the tail end of the slab 2 using the outlet-side inclined part 3b of a pair 1 of the anvils which are widened in the opposite direction to the advancing direction of the slab 2 by sending back the hot slab 2 this time. After that, the edging of the unexecuted part of press working of the hot slab 2 is successively executed by the outlet-side inclined part 3b and parallel part 4.