Provided is a control parameter automatic-adjustment apparatus that adjusts a control parameter which is used when a control apparatus of a plant calculates an operational control signal, the apparatus including: a simulator that simulates operation of the plant; a learning unit that searches for an optimal control parameter using the simulator; and a knowledge database that stores knowledge information which associates an amount of change in the control parameter with an amount of change in a state of the plant, in which the learning unit includes a search range determination unit that determines a control parameter search range based on the knowledge information that is stored in the knowledge database.