An optical apparatus is disclosed which has a minimized protruding portion at a portion where a plurality of barrel-constituting members are connected and which allows easy assembly and disassembly. The optical apparatus includes a first member and a second member which constitute a lens barrel for accommodating lenses and a connecting member which connects the first and second members together. The connecting member is formed of a plate-like member placed along the outer surfaces of the first and second members, is elastically deformed when the connecting member is attached to the first and second members, and pulls the first and second members in and connects them with elastic force caused by the elastic deformation.