1. A medical X-ray CT imaging apparatus comprising: an X-ray source for generating a cone beam; an X-ray detection part for detecting said cone beam; a supporting part for arranging said X-ray source and said X-ray detection part to be opposed to each other with a subject interposed therebetween; a subject holding part for holding said subject; a rotation driving part for driving said supporting part and said subject holding part to rotate relative to each other; an axis moving part for causing the rotation axis of said rotation driving part to be movable relative to said subject; a control part for automatically and consecutively performing X-ray CT imaging of respective imaging regions specified for a first living organ and a second living organ which are symmetrically located with respect to a predetermined plane by using said axis moving part and said rotation driving part; an image processing part for reconstructing respective CT images of said first living organ and said second living organ on the basis of an electrical signal which are obtained by said X-ray detection part through said X-ray CT imaging; and a display part for displaying said CT images of said first living organ and said second living organ which are obtained by said image processing part.