According to an embodiment, a semiconductor device including a first body molded with a first resin, a second body molded with the first resin, and a third body molded with a second resin. The first body includes a first light emitting element, a primary lead, a first light receiving element, and a secondary lead. The second body includes a second light emitting element, a primary lead, a second light receiving element, and a secondary lead. The third body includes the first body and the second body. At least one common lead includes the primary leads or the secondary leads, and a portion extending between the first body and the second body, the portion being covered with a first thin film linked to the first body and a second thin film linked to the second body.