The present disclosure relates to an air tight door including a frame having three frame members disposed, respectively, at a first lateral side, a second lateral side, and an upper side of an opening; and a longitudinal member disposed at a lower side of the opening. The door is rotatably connected to the frame member disposed at the first lateral side of the opening so as to open and/or close the opening. A first sealing disposed at each of the three frame members closely contacts the door in a closed state; and a second sealing elevatably disposed at a lower end of the door descends from the lower end of the door to closely contact the longitudinal member in the closed state. A locking device fixes a position of the door in the closed state; and an actuating device is configured to unlock the locking device.