OPTION MEMBER, BACKREST, AND CHAIR

To provide an option member, on which positioning can be easily performed, and a backrest and a chair that comprise the optional member.SOLUTION: An option member provided on a backrest of a chair comprises: a bracket attached to a backrest body; an option member body that slidably moves in the vertical direction with respect to the bracket; and a body to be operated that is attached to the option member body to move in the vertical direction together with the option member body. On the bracket is provided an engaging part. The body to be operated includes: a lever part that is to be operated by an operator; and a motion part on which a part to be engaged for engaging with the engaging part in an engaging direction is provided. Either of the engaging part and the part to be engaged represents a plurality of ones aligned in the vertical direction. Due to operation to the lever part, the motion part moves along the engaging direction.SELECTED DRAWING: Figure 5 【課題】位置調整を容易に行うことができるオプション部材、並びにそれを備えた背凭れおよび椅子の提供を目的とする。【解決手段】椅子の背凭れに設けられるオプション部材であって、背凭れ本体に取り付けられるブラケットと、ブラケットに対し上下方向にスライド移動するオプション部材本体と、オプション部材本体に取り付けられオプション部材本体とともに上下方向に移動する被操作体と、を備え、ブラケットには、係合部が設けられ、被操作体は、操作者によって操作されるレバー部と、係合部と係合方向に係合する被係合部が設けられる動作部と、を有し、係合部および被係合部のうち何れか一方は、上下方向に並んで複数配置され、動作部は、レバー部への操作により係合方向に沿って移動する、オプション部材。【選択図】図５