To provide a folding chair with which the leg frame can be lightened and the stacking efficiency can be improved.

The folding chair 1 consists of a front leg frame 2, which fixes the rear edge side 4b of a seat 4 rotatably in both directions, a rear leg frame 3, which fixes the front edge side 4b of the seat 4 rotatably in both directions, and a rotation supporter 5, which fixes the front leg 2 and the rear leg 3 rotatably in both directions relatively. The folding chair 1 can be folded from its used state P to its folded state Q by the relative rotation of the front leg 2, the rear leg 3 and the seat 4. The rotation supporter 5 is slid along the outside of the rear frame 3 between the used state P and the folded state Q.