1. A parameter adjustment device which adjusts a control parameter for a controller which calculates a manipulated variable by performing computation based on the control parameter, characterized by comprising: a model storage unit which stores a mathematical model of a controlled system in advance; a controller storage unit which stores, in advance, a controller algorithm by which the controller controls the controlled system; a constraint condition storage unit which stores a constraint condition on operation of the controller in advance; a simulation computation unit which performs a simulation on the basis of the constraint condition to simulate a control response of a control system including the controlled system represented by the mathematical model and a controller represented by the controller algorithm; an ideal control result storage unit which stores an ideal control response characteristic of the control system in advance; an evaluation function computation unit which computes an evaluation function value representing a proximity between a result of the simulation and the ideal control response characteristic; and a parameter search computation unit which causes said simulation computation unit to execute the simulation while sequentially changing the control parameter for the controller algorithm, and uses, as a parameter adjustment result, a control parameter which makes the evaluation function value become an optimal value.