PURPOSE: To enable employment of X-ray detectors to be used exclusively for transmitted image sensing and tomographic image sensing respectively, by a method wherein a means of collimating X-rays and an X-ray detector for tomography are put in one body and constructed so that they can be moved in parallel horizontally.

CONSTITUTION: In order to obtain a photoscopic image, a movable frame 201 is moved in parallel horizontally to a position whereat it does not become a hindrance on a course 106 of X-ray transmission to a two-dimensional X-ray detector 251, by a tomographic system mechanism control element 206 and a driving element 205. Thereby an X-ray generated from an X-ray focus 102 of an X-ray tube 101 is transmitted through a substance to be inspected on a sample stage 120 and falls on a plane of incidence of the X-ray detector 251. In order to obtain a tomographic image, the movable frame 201 is made to proceed into the X-ray transmission course 106 to a set position whereat a tomographic image is to be sensed. According to this constitution, the X-ray is collimated in the shape of a fan beam by an X-ray-side collimator 202, transmitted through a tomographic plane of the substance to be inspected and collimated by a detector-side collimator 203, with scattered light reduced, and then it enters an X-ray detector 204 for tomography.