Abstract: Disclosed is a lumbar supporting system of a chair and a chair having the same, and an object to be achieved by the present disclosure is to provide a lumbar supporting system of a chair and a chair having the same, which are capable of accurately supporting a user's waist according to the user's body type by adjusting a height and depth of a lumbar pad by using a vertical operating force.

Abstract: A chair with improved waist bearing power by self-weight is provided. A chair includes a supporting portion connected to a leg portion, a seat portion with one side connected to the supporting portion, a backrest post with other end installed to the supporting portion fixedly, a backrest frame with the one side connected to a top end of the backrest post, a backrest link having a top end portion inserted into a inserting groove formed in a lower-central rear surface of the backrest frame and a bottom end engaging the seat portion rotatingly, a link fixer connected to the backrest link rotatingly by a connecting axle and installed to the backrest post fixedly, and a backrest installed so as to be connected to the backrest frame and a top end portion of the backrest link and having flexibility.