PURPOSE: To easily calibrate and monitor flow controllers(MFC) without preventing other operations by providing plural interfaces which respectively correspond to one of plural MFCs and give voltage signals that correspond to their respective MFC control voltage and connecting a switching means with a display means.

CONSTITUTION: A monitoring device 1 monitors plural flow controllers(MFC) 10A to 10F, and interfaces 20A to 20F which are connected to each of the MFCs 10A to 10F respectively supply plural voltage signals which correspond to voltage control signals showing each of the MFC 10A to 10F operations. The MFCs 10A to 10F are connected to their corresponding transmission lines which are received by a cable 40, a switching means 60 is used to select a desired channel which corresponds to control voltage of any of plural MFCs 10A to 10F and control signals are supplied with plural indicators 70A and 70B after selecting the desired channel.