Optical apparatus

An optical apparatus comprising:

• an attached member;
• and
• an optical element attached to the attached member, and including:
• an optical function surface on which a coating layer is disposed;
• an outer peripheral surface;
• a flange part that projects from the outer peripheral surface in an outer periphery direction and including:
• an outer periphery part with a diameter thereof that increases toward a side contacting the attached member;
• a plane part connected to the outer periphery part outside the outer peripheral surface;
• a contact part provided on a side of the attached member and contacting the attached member;
• a first area where the coating layer is also disposed;
• and
• a second area where the coating layer is not disposed, the first and second areas being arranged along a circumferential direction,
• wherein the optical element and the attached member are adhered to each other with an adhesive while the optical element and the attached member contact each other,
• wherein, along a cross section of the optical element including an optical axis thereof and the first area, a length of the contact part is shorter than the length of the plane part,
• wherein only part of the outer peripheral surface and the first area of the flange part are covered with the adhesive, in an adhesion area where the optical element and the attached member are adhered to each other by the adhesive, without the second area being covered with the adhesive.