PURPOSE: To intensity strength of a radiation source without enlarging the focus of the radiation source, by arranging a radiant ray emitted from a plurality of radiation sources in such a way that it is emitted in a fan-shape from a single focus and detecting this radiant ray after passing through the specimen.

CONSTITUTION: A group of radiant rays 1 is shaped as a plurality of radiant ray sources 1-1W1-320 arranged in a fan-shape. By this, the plural radiant rays be have in such a way that they were emitted from an imaginery focus O. A collimetor 3 is attached to each radiant ray source. A specimen 4 is fixed on a turn table 4a. Radiant ray detectors 5-1W5-320 corresponding to a plurality of radiant ray sources are installed onto radiant ray source group 5. Thus, the focus of radiant ray source becomes smaller, and at the same time, its strength is intensified and space resolution capacity and permeability are improved.