The present invention provides a method for induction hardening of a steel member having an outer ring portion and, more specifically, for induction hardening of an outer circumferential surface of the outer ring portion. The method uses two pressing members, each of which includes a flat basal surface and a projecting portion projecting therefrom. Each of the projecting portions has a cross-section in the shape of a perfect circle. Also, the projecting portions have, on the outer circumferences thereof, respective pressing surfaces. While gaps are maintained between axial end faces of the outer ring portion and the basal surfaces of the pressing members, the pressing members are pressed against the outer ring portion so that the pressing surfaces each abut against the inner circumference side of the outer ring portion. While a biasing force is applied to the pressing members, the induction hardening process is applied to the outer circumferential surface. During the induction hardening process, the pressing members are moved toward each other until the basal surfaces abut against respective axial end faces of the outer ring portion.