To provide a flow control instrument which does not require a positioning operation as required in a conventional method in a surface mounting operation, and can simultaneously and uniformly carry out sealing connection by mounting a flow control device by means of fastening bolts, and especially has simple components and can easily mount and dismount the flow control instrument, and as a result, becomes compact in size.

In a structure for mounting the flow control instrument 3 by the surface mounting method, the body 11 of the flow control instrument 3 has an inlet port 12 and an outlet port 13 of fluid. Fastening bolts 17 for the surface mounting method are attached to both ends of the body 11 located outside positions of the inlet port 12 and the outlet port 13. The flow control instrument 3 is fixed to an attaching body 20 by means of the fastening bolts 17.