Method for manufacturing mirror device

A method for manufacturing a mirror device including a structural body that includes a support portion, a movable portion, and a coupling portion coupling the movable portion to the support portion such that the movable portion is swingable or movable, and a mirror layer provided on the movable portion, the method comprising:

• a first forming step of forming a plurality of parts on a wafer, each of the plurality of parts corresponding to the structural body;
• a second forming step of forming the mirror layer on a part of each of the plurality of parts, the part corresponding to the movable portion;
• a heating step of heating the part of each of the plurality of parts corresponding to the movable portion, after the first forming step and the second forming step;
• and
• a cutting step of cutting the wafer to separate the plurality of parts from one another, after the heating step, wherein
• in the heating step, the heating is performed in a state where the movable portion is swingable or movable relative to the support portion.