Abstract: A chair includes at least one support frame having two opposite side rails, a plurality of connectors mounted in each of the side rails of the support frame, and a plurality of elastic cords each mounted between the side rails of the support frame and each having two opposite ends each attached to one of the connectors. Each of the side rails of the support frame has a hollow inside provided with a slideway and has a side provided with a guide slot. Thus, each of the connectors is fully hidden in the slideway and the guide slot of each of the two rails of the support frame so that each of the connectors will not be exposed outwardly from the support frame to enhance the outer appearance and safety of the chair.