Disclosed in this application is a chair capable of permitting a user to quickly and easily change his or her posture by tilting a back support in a state in which the user takes a seat. The chair includes a seat support; a back support which has a back frame, with a lower end being connected to a rear end of the seat support by a pivot shaft, so that the back support is tilted in a rearward direction; and a footrest which is engaged to the seat support, so that the back support is interlocked with the footrest.