A folding chair comprises a seat, a back, an interlinking device, a front leg, and a rear leg. The seat, the back, the interlinking device, the front leg, and the rear leg are interlinked. The seat comprises at least one guiding portion, and the interlinking device comprises at least one actuating member, which is movably coupled to the guiding portion. A user can fold or unfold the folding chair by a single-handed operation, such as pushing or pulling on the back or pulling a handle.