To provide a control unit which can control the operation of a plant while maintaining high controllability according to accurate operation standards without any discrimination between a batch operation system and a continuous operation system.

The unit 40 is a device which controls the operation of the plant 10 and is equipped with a storage means, a measured value acquiring means, and a control means, and the plant is operated through an operating means 32 of the plant to control the temperature of contents in a reactor 12 to a target value. The storage means stores a target value for temp., a set manipulated variable setting the quantity of manipulation and a set wait time prescribed as a delay time of control. The measured value acquiring means acquires the measured value of temp. from a thermometer 20 provided in the plant. The control means compares a measured value obtained by the measured value acquiring means with the target value read out of the storage means at intervals of a set wait time and reads a set manipulated variable out of the storage means if the measured value deviates from the target value to send a command for operating the plant by the set manipulated variable to the operating means provided for the plant.