In accordance with an embodiment, a plant control apparatus includes a deviation calculation unit, a velocity-type PID calculation unit, a plurality of integral calculation units, a plurality of overwrite units, and an automatic balance unit. The deviation calculation unit calculates a deviation between a process value from a plant with operation terminals and a set value corresponding to a control object, and generates a deviation signal. The velocity-type PID calculation unit generates a velocity-type operation amount command signal corresponding to the deviation. The integral calculation units generate position command signals as defined operation terminal position command signals. The overwrite units generate additional position command signals to perform overwrite processing and newly define operation terminal position command signals. The automatic balance unit calculates a deviation between the defined operation terminal position command signals, corrects the operation amount command signal and supplies the corrected operation amount command signal.