A tomography system includes a radiation source, a radiation detector, a subject table, an imaging unit and a reconstruction unit. The imaging unit obtains a projection image a predetermined number of times while changing a positional relationship of the radiation source and the radiation detector. The reconstruction unit generates a tomogram of a subject using the projection image obtained by the imaging unit. The reconstruction unit includes a correction unit. The correction unit performs correction processing to (i) create a profile of a pixel signal value from a no-subject-included projection image obtained by the imaging unit without the subject on the subject table and (ii) correct, on the basis of the created profile, a subject-included projection image obtained by the imaging unit with the subject on the subject table or a detection probability used in generating the tomogram.