To propose a method of forming a stainless steel slab in a sizing press by which the reduction of the amount of movement of a seam flaw in the tip and the tail end and the obtainment of a hot-rolled stainless steel strip the width of which is uniform over the entire length are compatible.

When the amount of width press in the tip and tail end portions of a slab is made larger than the amount of width press in a wide part by a stepping press method, one strike is performed with the sizing press so as to satisfy the next formulas to the tip and tail end portions. Description: the tip part: 0parameter A1.3, A=(a1+5b1)/t, the tail end part: 0parameter A1.3, A=(a2+5b2)/t. Where, t is the thickness of the slab, the amount of inverse step in the tip and tail end portions a1, a2 are the width difference to one side measured from an edge by taking the width in the wide part where is formed by applying the stepping press method to the approximately rectangular slab before the width press as a standard. The lengths b1, b2 of the inverse stepped part are the distances to the end of the inverse stepped part measured from the tip and the tail end.