Method of manufacturing mirror device

A method for manufacturing a mirror device comprising a structure including a base portion and a movable portion supported on the base portion, and a mirror layer provided to the movable portion, the method comprising:

• a first step of preparing a wafer having a support layer and a device layer;
• a second step of forming a slit in the wafer such that the movable portion becomes movable with respect to the base portion by removing a part of each of the support layer and the device layer from the wafer by etching and forming a plurality of parts each corresponding to the structure in the wafer, after the first step;
• a third step of performing wet cleaning for cleaning the wafer using a cleaning liquid after the second step;
• and
• a fourth step of cutting out each of the plurality of parts from the wafer after the third step,
• wherein in the second step, a circulation hole penetrating the wafer is formed at a part other than the slit in the wafer by the etching,
• wherein in the third step, the wet cleaning is performed such that the cleaning liquid flows through the circulation hole formed in the second step.