To provide a foldable chair capable of performing the slide moving motion and the turning motion of a seat board smoothly.

In the foldable chair 1 holding a seat board 2 on a seat board holding member 3 in an upright attitude during no use and to be used by turning a seat board 2 into attitude approximately parallel to the ground by enabling the turn of the seat board 2 by sliding and moving the seat board 2 upwards from such an attitude, the folding chair is provided with a turn supporting shaft 33 attached to the seat board holding member 3 to be engaged into a long hole 24 of the seat board 2 relatively and freely movably, a sliding movement guide part for guiding the sliding movement in the upright attitude of the seat board 2, and a turning motion guide part for guiding the turning motion of the seat board 2 by holding the lower part of the seat board 2 for holding the relative positions of the long hole 24 and the turn supporting shaft 33 when turning the seat board 2.