An ion beam irradiation apparatus includes modules for generating an ion beam according to a recipe, and a control device. The control device receives the recipe including a processing condition for new processing, reads, from a monitored value storage, a monitored value that indicates a state of a module during a last processing immediately before the new processing, inputs the processing condition and the monitored value to a trained machine learning algorithm and receives, as an output from the trained machine learning algorithm, an initial value for the module, and outputs the initial value to the module to set up the module for generating the ion beam.