To automatically watertightly press a door body into contact with a frame body by means of a device having a simple structure.

This watertight door device is formed by providing a frame body 1 watertightly fixed to the opening part 3 of a partition wall 2, and having a packing 4 at an abutting surface relative to a door body 10, and the door body 10 slidably installed along the frame body 1 and airtightly pressure- contacting the packing 4. Where, each wedge type plate 2 is projected on both the side edge parts of the door body 1 facing both the end edge parts of a device frame 5. Each clamping bolt 13 having a rotatably buried ball 13a at its extremity is projected on the positions of the end edge parts of the device frame 5 meeting the wedge type plates 12 at a position closing the door body 10. Closing the door body 10 cooperates the wedge type plates 12 with the clamping bolts 13 to automatically press the door body 10 into contact with the frame body 1.