The invention relates to an apparatus and method for compensation of three-dimensional movements of a target volume (1) during ion beam irradiation. For the purpose, the apparatus comprises a position location and tracking system (4) for detecting the movements and a depth modulator (6) for modifying the depth of penetration of the ion beam. For the purpose of compensation, the movements are divided vectorially into a transverse component and a longitudinal component. The transverse component is compensated from irradiation point to irradiation point using the raster scanning apparatus (3) and the longitudinal component is compensated from irradiation point to irradiation point using the depth modulator (6) by means of the fact that, in addition to the change in the location of the target volume, the change in the structure of healthy tissue covering the target volume is, in the preliminaries to irradiation, detected and modelled and stored in the form of a look-up table in a memory of a movement measurement, control and read-out module SAMB and compared with the actual values during irradiation.