To provide a method for producing an Fe-Ni based alloy material for a press forming type flat mask which can be imparted with excellent press formability by being anhealed before press forming.

The Fe-Ni based alloy material for the press forming type flat mask having a composition containing 33 to 37% Ni and 0.001 to 0.1% Mn, voluntarily containing 0.01 to 2% Co, and containing one or more kinds selected from 0.01 to 0.8% Nb, 0.01 to 0.8% Ta and 0.01 to 0.8% Hf by 0.01 to 0.8% in total, and the balance Fe is hot-rolled, is thereafter repeatedly subjected to cold rolling and annealing, and is subjected to final annealing and final cold rolling to produce the Fe-Ni based alloy material. In this production method, the grain size number in the final annealing is controlled to 9.0 to 12.0, and the working degree in the final cold rolling is controlled to 40 to 75%, so that its press formability is improved.