A steel sheet, of which the contents, which are expressed in mass%, of elements in chemical components fulfill both the requirement represented by formula (1) and the requirement represented by formula (2), a Ti-containing carbonitride is contained as an intercalated material, and the number density of a portion of the Ti-containing carbonitride which have a long side length of 5 mum or longer is 3 particles/mm2 or less. 0.3 <= {Ca/40.88+(REM/140)/2}/(S/32.07) (1) Ca <= 0.005-0.0035C (2).