Chair

A chair comprising:

• a seat;
• a backrest tiltable with respect to the seat;
• and
• a support structure supporting the seat and the backrest, wherein
• the backrest includes:
• an arm portion supported by the support structure;
• and
• a back support portion positioned above the arm portion in a vertical direction and supported by the arm portion, and
• the support structure includes:
• a first shaft portion extending in a first direction intersecting the vertical direction and rotatably supporting the seat;
• a second shaft portion positioned behind the first shaft portion in a second direction intersecting the vertical direction and the first direction, extending in the first direction, and rotatably supporting the seat;
• a third shaft portion positioned below the first shaft portion in the vertical direction, extending in the first direction, and rotatably supporting the arm portion;
• a fourth shaft portion positioned behind the third shaft portion in the second direction and extending in the first direction;
• a support base supporting the third shaft portion and the fourth shaft portion;
• an arm support portion rotatably supported by each of the first shaft portion and the third shaft portion, tiltable with respect to the second direction in conjunction with rotation of the arm portion around the third shaft portion, and supporting the arm portion;
• and
• a support link including a first link support portion rotatably supported by the second shaft portion and a second link support portion rotatably supported by the fourth shaft portion, and positioned behind the first shaft portion and the third shaft portion in the second direction.