PURPOSE: To perform a stable fuel supply control against a load variation in which a phase displacement caused by a delay in responding speed between fine powder coal fuel and heavy oil fuel is eliminated and occurrence of distur bance is prevented.

CONSTITUTION: A load distribution outputted from a load adjusting unit 10 is distributed by distributors 12 and 13 in response to a distribution rate αset in advance by a rate setting unit 11, the load instruction is given to a flow rate adjusting meter 14 of a fine powder coal control system and to a flow rate adjusting meter 15 of a heavy oil control system so as to control a fine powder coal flow rate and a heavy oil flow rate supplied to a boiler 1, respectively. Instruction values outputted from the flow rate adjusting meters 14 and 15 are given to a calculator 17, a real feeding rate β of fine powder coal is calculated, this calculated value is given to a comparator 18, compared with the rate α set by the rate setting unit 11 so as to discriminate if the real feeding rate β of fine powder coal is within a certain range in respect to a reference rate set by a rate setting unit. If the value is within the range, the load instruction inputted from the distributor 12 into the flow rate adjusting meter 14 is fixed by a holding unit 19.