To provide a fluid control system for smoothly and speedily elevating and tilting a chair for dental use or the like.

The chair 10 having an upper structure comprising a seat 16 and a backrest 18 is vertically moved by an elevation cylinder 22, and the backrest is tilted by a tilting cylinder 24 in this fluid control system 28. A gear pump 42 is provided to be actuated in two directions connected to a first fluid supply circuit connected to the elevation cylinder and a second fluid supply circuit connected to the tilting cylinder. A motor 38 rotatable in two directions is connected to the gear pump. A fluid holding reservoir 44 and a series of check valves 64, 66, 68 and 70 are provided. For moving the chair up, the check valves are actuated to close the second fluid supply circuit, and open the first fluid supply circuit to actuate the elevation cylinder. For tilting the backrest, the check valves are actuated to close the first fluid supply circuit, and open the second fluid supply circuit to actuate the tilting cylinder.