Abstract: A safety device for a folding chair has an adjustable brace for attachment to spaced-apart legs of a folding chair for preventing the chair from collapsing under weight. The brace includes two telescopic tubes and a locking mechanism that releasably locks the tubes together in a position that securely interposes the brace between the legs with the brace securely engaged with each leg. The overall length of the brace is adjusted to provide the most stable support to the chair. First and second leg engaging elements have a Y-shape configuration with an open curved portion and an extended leg portion. The open curved portions fit snugly around the chair legs. In a further embodiment, fasteners are provided on opposed ends of the open curved portions and the curve portions are overlapped so as to receive and encircle a chair leg to secure the brace to the folding chair.