Fixing device, fixing method, and structure

A device for fixing members, in which a plurality of members are placed in a layered manner between a die and a punch disposed in an opposed manner, and the plurality of members are pressed and fixed by the die and the punch relatively moved so as to come closer to each other, wherein

• the plurality of members include a first member including a first fixation portion, a second member including a second fixation portion smaller than the first fixation portion, and a third member including a third fixation portion larger than the second fixation portion,
• the die includes a projected portion that protrudes toward the punch,
• the punch includes a sheltering portion recessed along a shape of the second fixation portion, and
• the die and the punch are relatively moved so as to come closer to each other and press the first fixation portion and the third fixation portion, thereby forming an extruded portion and forming a recess-projection fitting structure in a thickness direction, so that the second fixation portion is sandwiched and fixed between the first fixation portion and the third fixation portion.