The purpose of the present invention is to make it possible to efficiently and accurately generate an ultrasonic tomographic image and an optical coherence tomographic image of the same location with the same orientation. In order to achieve this, the image diagnostic apparatus stores, in a memory, ultrasonic line data and optical coherence line data radially extending from the center of rotation on the basis of signals obtained by executing a scanning process, and calculates a provisional number of offset lines which indicates a relative deviation of the ultrasonic line data corresponding to the optical coherence line data stored in the memory on the basis of the distance between an ultrasonic transceiver unit and an optical transceiver unit, and the speed of rotation and speed of movement of an imaging core in the scanning process. The image diagnostic apparatus determines a retrieval starting position for the optical coherence line data and the ultrasonic line data on the basis of the provisional number of offset lines, and initiates the retrieval from the retrieval starting positions and retrieves line data having a predetermined characteristic. The image diagnostic apparatus calculates the relative deviation of the optical coherence line data corresponding to the retrieved ultrasonic line data as a real number of offset lines. Thereafter, the image diagnostic apparatus reads the ultrasonic line data while shifting the ultrasonic line data by the real number of offset lines relative to the optical coherence line data in order to generate an optical coherence tomographic image and an ultrasonic tomographic image.La présente invention vise à permettre de générer, efficacement et avec précision, une image tomographique à ultrasons et une image tomographique à cohérence optique du même emplacement avec la même orientation. À cet effet, l'invention concerne un appareil de diagnostic d'image qui stocke, dans une mémoire, des données de ligne d'ultrasons et des données
