A control device includes a primary control unit which computes a manipulated variable and outputs it to an actuator of the primary control system; a secondary control unit which takes as input an equilibrium point setpoint representing an equilibrium point which is the desired manipulated variable output in steady state of primary control, takes the manipulated variable of the primary control system as process variable input, computes an adjusted manipulated variable, and outputs it to an actuator of the secondary control system; and an equilibrium point setpoint determination functional unit which detects a state in which the setpoint of the primary control system is maintained at the same value for a pre-specified period of time or longer as a steady state, computes an equilibrium point, and sets this equilibrium point setpoint in the secondary control unit.