STEEL BAR

A steel bar according to one embodiment of the present invention includes predetermined chemical composition, wherein a quenching deflection in a cross section is 1.5 mm or less, wherein ”max and ”min is 1.5 mm or less, wherein a structure in a surface layer area includes 10 area% or less of ferrite and a remainder including one or more selected from a group consisting of a bainite and a martensite, wherein an average value of the grain size of a bcc phase in the surface layer area is 1.0 to 10.0 µm, wherein an average value of the grain size of the bcc phase in a center area is 1.0 to 15.0 µm, wherein a hardness of a region of which a depth from the surface is 50 µm is Hv200 to Hv500, and wherein a total decarburized layer thickness DM-T is 0.20 mm or less.