A chair includes a support base body portion; a backrest rotatably supported with respect to the support base body portion on an axis in a width direction of the support base body portion and being displaceable from an initial state to an inclined state of being inclined rearward; a biasing member configured to bias the backrest in the inclined state, in a direction of returning to the initial state; an adjuster configured to adjust a biasing force of the biasing member; and an operating member joined to the adjuster and configured to operate the adjuster, wherein the biasing member is provided in the backrest or the support base body portion, the adjuster is provided in the backrest, and the operating member is disposed behind the axis and on one side of the backrest in the width direction.