A PID adjustment support device has: a recognition tolerance interval storing portion for storing, in advance, a recognition tolerance interval understood by a user regarding target quantity data of a model to be controlled; and a display processing portion for graphing and displaying, on a displaying portion, the target quantity data and, as a modeling result, a model-response waveform that is a control-response waveform calculated based on the model to be controlled, and for overlaying with the modeling result and displaying the recognition tolerance interval stored in the recognition tolerance interval storing means.