PROBLEM TO BE SOLVED: To provide a radiation tomography apparatus that is improved in precision of correction in scattered radiation correction in which a geometric scattered radiation incidence rate between detection elements is not considered.SOLUTION: A scattered radiation correction is performed to projection data obtained by detection elements of a radiation detector, using a first correction value A determined based on the projection data and a second correction value B determined based on the position of the detection elements. For example, a first correction value A defines the ratio of the component of the scattered radiation in the projection data obtained by the detection elements, and a second correction value B defines a relative value of a geometric scattered radiation incidence rate in the detection elements. The scattered radiation component in which the variation of the geometric scattered radiation incidence rate between the detection elements is removed can be obtained, by multiplying a scattered radiation component estimated by the first correction value A by the second correction value B.
