Provided is a chair suited to the use of a keyboard or mouse, the chair has a seat 3 and a rocking backrest 4. The seat 3 comprises a first section 3a, 12a and a second section 3b, 12b. The first section 3a of the seat 3 is affixed to a seat-mounting shell 11 is attached to a base 9, via a seat-mounting fixture, so as to be slide forwards and backwards. The backrest 4 has a back cover 14, a back panel 15 and a cushion move downwards while rotating in a seesaw fashion during rocking. The front end of the back cover 14 is connected to the seat-mounting fixture 10 by means of a connecting pin 25. When the chair rocks, the seat 3 moves forwards as a whole while the second section 3b tilts backward.