PURPOSE: To prevent pressure fluctuation of main steam by maintaining the coaling quantity of all of the pulverizers into the boiler at a prescribed value at all times, in the system where coaling quantity from pulverizers into the boiler is controlled.

CONSTITUTION: In order to maintain the pressure of main steam at a constant value after the operation of coal feeder A is started, value (a) plus value (b) is substracted from value (c) during time t4; where value (c) is an amount of coal supplied from feeder A to pulverizer A' during time t3, value (b) is an amount of coal supplied from feeder A to pulverizer A' during time t4, and value (c) is an amount of coal fed to boiler from pulverizer B'WF' which have already started operation. In order to satisfy the above relation, signal d is generated setting t2, t4 and Y rpm, where secular change of pulverizer A' is taken into consideration. Signal d is supplied to the feeder A for starting operation, then, at the same time, the same signal and signal b which is the rotation instruction signal for the feeders BWF are sent to each of the feeders BWF thru the adder H and the controller PI. During the time t4, revolutions of the feeders BWF are reduced and subsequently, coaling quantity of all of the pulverizers into the boiler is maintained at a prescribed value.