1. An X-ray imaging apparatus for capturing an X-ray tomogram of an object, comprising: a selection unit configured to select two X-ray focuses out of a plurality of X-ray focuses which project images on an X-ray detector through a region of interest which is an imaging region of the object, the selected two X-ray focuses having an intersecting angle of a predetermined value in the region of interest; and a control unit configured to control the X-ray focuses existing between the selected two X-ray focuses to emit X-rays and to control the X-ray detector to detect the emitted X-rays, for capturing an X-ray image, wherein, after the two X-ray focuses are selected by the selection unit, the selection unit selects other two X-ray focuses by decreasing the intersecting angle in the region of interest.