To securely lock a leg of furniture when the leg is folded and a support rod top is moved to the inner end of a passage, and to enhance the safety of the folded leg so that the furniture can be easily carried.

The passage 9 is formed of a long narrow plate 8 on the rear side of a top board 24, and by sliding the support rod top 2 inside the passage 9, the leg can be brought up/down. A bushing 10a is formed at the inner end of the passage 9. A lock plate 3a made of a thin plate is formed in an arc angled shape with a ejecting inclined edge 5a and a lock inclined edge 6a continued thereto. A handle lever 23a is extended from under the lock plate 3a, and the end 23' of the handle lever is made to swell in the same direction as the lock plate 3a. The front of the lock plate 3a is rotatably attached to a rotation shaft 4a attached under the passage 9. The lock plate 3a is usually made to project into the passage 9 by a coil spring 7. When the leg is folded, the support rod top 2 is located on the bushing 10a side via the lock inclined edge 6a and the end 23' is pressed on the top board 24 side. When the handle lever 23a is brought down, the lock plate 3a is freely removed from the passage 9.