A flow control device is provided comprising:
a housing (19) including a first chamber (21) communicated with an inlet port (11) and a second chamber (22) communicated with an outlet port (12); a cylindrical portion (25), which extends in the second chamber, for communicating the first chamber with the second chamber; a valve seat (61) provided at a forward end portion (25a) of the cylindrical portion; and a valve body (32) for opening and closing the valve seat, wherein at least one of the valve seat and the valve body is made of a material, the heat deformation of which is smaller than that of material composing the cylindrical portion. Due to the foregoing, it is possible to stably adjust the flow rate of a fluid of a high temperature and pressure. A pressure chamber (29), which is communicated with the second chamber and provided with a pressure port (18), may be arranged in the housing. A first and second flexible separation means (41, 51), which are connected to each other, for separating the second chamber and the pressure chamber from each other may be provided and a bed (75) arranged between the first and the second flexible separation means may be also provided. A reinforcement member (90) may be embedded in the cylindrical portion (25).