To reliably prevent entrance of electro-magnetic waves in a door that closes an opening portion formed in an airframe of an aircraft. A gasket seal 20 which is arranged between an opening portion 12 formed in an airframe of an aircraft and a door 13 for closing the opening portion 12, includes: a gasket seal body that is made of a rubber material; and conductive fiber 24 that covers a surface of the gasket seal body. When the door 13 is in a closed state, the gasket seal 20 whose surface is made conductive is abutted against a striker 30 provided on a skin 11 side of the airframe and made of a conductive material. The door 13 and the skin 11 of the airframe are electrically connected together via the conductive fiber 24 and the striker 30, and electro-magnetic waves can be reliably shielded.