The objective is to obtain a particle beam irradiation apparatus in which an irradiation position relevant value related to the irradiation position of a charged particle beam and an irradiation position relevant value errorcan be displayed in such a way that the irradiation position relevant value and the irradiation position relevant value error correspond to each other. There is provided a data processing apparatus (19) that displays on a display unit (43) a measured irradiation position relevant value and an irradiation position relevant value error, which is the error of the measured irradiation position relevant value related to the irradiation position of charged particle beam (1) with respect to a desired irradiation position relevant value related to a desired irradiation position, in such a way that the measured irradiation position relevant value and the irradiation position relevant value error correspond to each other and the data processing apparatus (19) has a calculation unit (42) that displays a desired value display figure (23) indicating a desired irradiation position relevant value at the coordinates of the desired irradiation position relevant value and a measured value display figure (24) at display coordinates, which are coordinates obtained by adding the desired irradiation position relevant value to the coordinates acquired by arithmetically operating an irradiation position relevant value error with deformation coefficients, and that displays a line (25) that connects the measured value display figure (24) with the desired value display figure (23).
