A method includes: sandwiching a plastic layer between a glass substrate and a metal plate made of an iron-nickel alloy and joining the metal plate to the glass substrate with the plastic layer in between; forming a mask portion including a plurality of mask holes from the metal plate; joining a surface of the mask portion that is opposite to a surface of the mask portion that is in contact with the plastic layer to a mask frame, which has a higher rigidity than the mask portion and is in a shape of a frame surrounding the mask holes of the mask portion; and peeling off the plastic layer and the glass substrate from the mask portion.