The invention relates to a steel sheet, a surface-treated steel sheet, and a method for producing the same. The high-strength steel sheet having excellent bending strength in the form of a tensile strength of 590 MPa or higher has a chemical composition of C: 0.03 to 0.20%, Si: 0.005 to 2.0%, Mn: 1.2 to 3.5%, P=0.1% or less, S=0.11% or less, sol. Al: 0.001 to 1.0%, N=0.01%, and Bi: 0.0001 to 0.05%; arbitrarily contains Ti<=0.3%, Nb<=0.3%, V<=0.3%, Cr<=1%, Mo<=1%, Cu<=1%, Ni<=1%, Ca<=0.01%, Mg<=0.01%, REM<=0.01%, Zr<=0.01%, and B<=0.01%; and has an Mn segregation ratio (Mnmax/Mnav) of less than 1.30 as calculated from the average Mn concentration (Mnav) and the maximum Mn concentration (Mnmax) at a position of (1/20) the depth of sheet thickness from the steel sheet surface.