PURPOSE: To provide the gas flow rate controller which keeps the gas flow rate fixed regardless of the change of the gas pressure.

CONSTITUTION: Based on the gas flow rate setting signal outputted from a gas flow rate setting means 31, an inflammable gas setting reference signal and a supor-burning gas setting reference signal are outputted in the ratio preliminarily determined by a ratio setting means 32. Comparison means 42 of control units 33 and 34 compare these reference signals with the flow rate of inflammable gas and that of supor-burning to a burner for soldering detected by flow rate detection means 43, and control valves 44 are subjected to feedback control so that the differences are 0, and flow rates of gas to the burner are controlled, thereby keeping the mixture ratio of gas to the burner constant regardless of the change of the gas pressure.