Method for producing Fe-Ni alloy sheet, and Fe-Ni alloy sheet

A method for producing an Fe-Ni alloy thin sheet and an Fe-Ni alloy thin sheet, characterized in that a hot-rolled material having a thickness of 2 mm or more, in mass%, is used to form a cold-rolling blank material, the hot-rolled material having a Ni + Co content of 35.0-43.0% (wherein Co is 0-6.0%), Si content of 0.5% or less, Mn content of 1.0% or less, and the balance being Fe and impurities, the cold-rolling blank material is subjected to a first cold rolling at a reduction rate of 85% or more, and after the first cold rolling, the first cold rolling is performed with a second cold rolling at a reduction rate of 85% or more, and the second cold rolling is performed with a third cold rolling at a reduction rate of 85% or more. The method is characterized in that a Fe-Ni alloy sheet having a thickness of 0.25 mm or less is produced by performing recrystallization annealing under conditions of a temperature of 800 DEG C or more and a holding time of 0.1-1.2 minutes, after the recrystallization annealing, p