A device for converting a regular cockpit door and its surrounding traffic area for a cockpit security door/restroom 10, to prevent intrusion into the cockpit 53 during a route, having a bulletproof case 12 installed on a hardened wall 17 isolating the cockpit 53 from the cabin 52. The case 12 basically contains in its interior: a toilet 24, a sink 91, various panoramic-one-way lenses 42 to observe the cabin 52, a security service window 30 to receive meals, drinks, etcetera from the cabin 52; it also is provided with an ambient air purifier unit 81 and a bifold door 11 or curtain to provide privacy from other crewmembers while utilizing the facilities. The case performs as a door at beginning or end of a route, as a restroom during the route, and takes almost no needed space from the aircraft 13 or other means of transportation, while functioning to provide security and comfort to cockpit crewmembers.