The present invention provides a method for producing a peptide, characterized in that it comprises converting an —SH group of a peptide comprising an amino acid residue having the —SH group to an —OH group, wherein said method comprises the following steps (a) to (c): (a) allowing an —SH group in a peptide to react with a methylating agent to convert the —SH group to an —SMe group; (b) allowing the —SMe group obtained in the step (a) to react with a cyanizing agent to produce a reaction intermediate; and (c) converting the reaction intermediate obtained in the step (b) to a peptide comprising an amino acid residue having an —OH group under more basic conditions than the conditions in the step (b).