To provide a light-weight compactly foldable chair for which the strength of supporting legs is increased, an armrest position is made appropriate and the angle follow-up ability of a backrest part is imparted.

In this foldable chair, four supporting legs 2a, 2b, 3a, and 3b are composed of a lower pipe 4 of a small diameter and an upper pipe 5 of a large diameter fitted to the lower pipe 4 freely slidably in an axial direction. A lower connection member 6 for connecting the end part of a reinforcing member 13 is provided on the lower end part of the lower pipe 4 and an upper connection member 8 connected to the end part of the reinforcing member 13 is provided on the upper pipe 5. Accompanying the turning of the reinforcing member 13, the lower end of the upper pipe 5 is contracted to abut on the lower connection member 6 at the time of assembly and two legs 2a and 2b of the four supporting legs are extended by the projection of the lower pipe 4 from the upper pipe 5 at the time of folding.