Method for producing annealed and pickled steel sheet

A method for producing an annealed and pickled steel sheet in a continuous manner by continuously performing:

• subjecting a cold-rolled steel sheet to annealing in an annealing furnace by feeding the cold-rolled steel sheet through the annealing furnace to obtain an annealed steel sheet;
• subjecting the annealed steel sheet discharged from the annealing furnace to pickling with a mixed acid solution containing a first acid that is oxidizing and a second acid that is non-oxidizing, by feeding the annealed steel sheet into a mixed acid tank holding the mixed acid solution;
• and
• subjecting the annealed steel sheet discharged from the mixed acid tank to repickling with an acid solution containing a third acid that is non-oxidizing, by feeding the annealed steel sheet into an acid tank holding the acid solution, to thereby obtain an annealed and pickled steel sheet, wherein
• Fe concentration in the mixed acid solution in the mixed acid tank is measured, and
• a lower limit of ferrite fraction in a surface layer of the annealed steel sheet to be subjected to the pickling is set according to the Fe concentration measured.