There is obtained a particle beam irradiation apparatus which does not use any IF sentence (conditional expression for case classification) and can calculate a control command and enhance irradiation position precision. The particle beam irradiation apparatus is provided with inverse mapping means having an inverse mapping mathematical expression model for generating an command value for the scanning electromagnet from a desired irradiation position coordinate of the charged particle beam in an irradiation subject so that irradiation to the irradiation subject is implemented on the basis of the command value concerned, and the scanning electromagnet is controlled on the basis of the command value generated from the desired irradiation position coordinate of the charged particle beam in the irradiation subject by using the inverse mapping mathematical expression model, thereby irradiating the irradiation subject with the charged particle beam while scanning the charged particle beam.