Abstract: A chair, especially an office chair, includes a seat that is fastened on a base support unit, a backrest that includes a back lower region and an upper shoulder region and is fastened to a back support, the back support being supported by the base support unit in a manner permitting rotation about an inclination axis. The shoulder region is connected to the back support in a manner permitting inclination about a shoulder axis and is hinge-connected to a back lower region at a lumbar region, and the back lower region further extends along a chair element so that when the shoulder region is inclined about the shoulder axis, an angle of the shoulder region relative to the back lower region is changed.

Abstract: A chair includes a support device that is capable of fitting support devices of another chair, a backrest that is attached to the support device or an intermediate support member provided for the support device so that the backrest is capable of being tilted rearwards, and a seat that is capable of being raised from an unfolded posture to a raised posture overlapping with a front side surface of the backrest, a plurality of chairs being capable of being fitted with each other back and forth by raising the seats thereof. The seat is attached to the support device, the backrest or the intermediate support member so that the seat is capable of being raised and rotated and so that the seat is capable of taking at least one movement of forward movement, retreat movement and tilting at the unfolded posture.

Abstract: A rocking chair includes a seat, a backrest that is tiltable rearward, a locking spring portion that imparts resistance to the rearward tilting of the backrest, and a resilience adjustment member that changes the degree of resistance of the spring portion to the rearward tilting of the backrest. The resilience adjustment member is a cam that is rotationally operable by a person seated on a seat and the position in which rocking load due to the rearward tilting of the backrest is applied to the spring portion is changed by the cam, so that moment applied to the spring portion changes and the degree of resistance of the spring portion is adjusted.