Abstract: The present device relates to a chair in which a base member is fitted onto an upper portion of a leg comprising a plurality of castors in contact with a floor together with support members for these castors, and a seat portion and a back rest are provided on an upper portion of a support plate that is capable of reclining with respect to the base member. This chair is also provided with a cam-shaped link capable of rotating about the periphery of a pin provided in the base member, an upper portion of the link protrudes towards the support plate side, and a corresponding elastic member that is compressed by the rotation of the link is provided in a bottom portion of the base member. A shaft portion in contact with the link, and which causes the link to change profile in response to the reclining action, is provided within the support plate. This configuration provides a chair that is inexpensive and can naturally adopt either a serious working position or a relaxed reclining position.