PURPOSE: To generate door locking stably in a plurality of places by allowing clamp of the first joint lock to rotate in the direction opposite the handle rotating direction, and interlocking the clamp of another joint lock with the first.

CONSTITUTION: A plurality of joint locks 72, 71, 72 are provided in vertical arrangement in the neighborhood of one edge of a door on its opening side, and the first joint lock 71 in the middle is provided with a handle which is rotate clamps 10... through an inverting mechanism. The clamp 10 of the second joint lock 72 is coupled with the clamp 10 of the first through coupling rods 73, 73. When the handle is rotated in the direction A, the clamp 10 of the first joint lock 71 rotates in the B direction and detained with a frame in the sunk position from above, and locking is generated in the condition stable with the own weight. Further the clamp 10 of the second joint lock 72 interlocks with the clamp 10 of the first joint lock 71, and certain locking is obtained in a plurality of places.