Disclosed are the steam generator and the washing/drying machine having the same, the steam generator including: a case having an opening at one side thereof, a heating unit formed to penetrate the opening, and a fixing assembly mounted at the opening so as to seal the opening and supporting the heating unit, wherein the fixing assembly includes a sealing member for sealing the opening, and the opening includes a leakage prevention portion for preventing a gap formation between the opening and the sealing member when the sealing member is deformed, thereby preventing a leakage between the opening of the case and the sealing member even though the case or the sealing member is thermally deformed.