1. A radiographic apparatus having a radiation emitting device for emitting radiation toward a patient, and a radiation detecting device for detecting radiation transmitted through the patient, to carry out radiation image pickup by obtaining radiographic images based on the detected radiation, the radiation emitting device and the radiation detecting device being constructed movable parallel relative to each other in the same direction along a longitudinal direction of the patient, the radiation emitting device intermittently emitting radiation and the radiation detecting device detecting radiation transmitted through the patient irradiated intermittently whenever the radiation emitting device and the radiation detecting device move every predetermined distance relative to the patient, said apparatus comprising an image decomposing device for decomposing the radiographic image for the every predetermined distance, an image composing device for composing the decomposed images for each of the same projection angles to obtain a projection image for each projection angle, and a reconstruction processing device for carrying out a reconstruction process based on the composed projection images to obtain a sectional image.