An optical subassembly (OSA) with a newly arranged optical device is disclosed. The OSA provides a ceramic package that installs a semiconductor optical device, a joint portion welded to a lid of the ceramic package, and an optical coupling portion that receives an external optical fiber. In the OSA, the seal ring put between the top of the multi-layered ceramic package and the lid is isolated from the optical device; accordingly, the lid, the joint portion and the optical coupling portion are electrically isolated from the semiconductor optical device even when the OSA is installed in an optical apparatus such as an optical transceiver.