1. An X-ray CT apparatus having a support means with an X-ray generator and an X-ray detector faced to each other that is relatively rotated around an object disposed between said X-ray generator and said X-ray detector, said X-ray CT apparatus rotating said support means for executing a CT for a local region of said object; and said X-ray CT apparatus further moving said X-ray generator and said X-ray detector along an orbit for a panoramic radiography for executing the panoramic radiography; said apparatus comprising: an image data input means for taking in attribute information of an X-ray image data outputted from another X-ray apparatus different and external from said X-ray CT apparatus the X-ray image data comprising a panoramic image obtained by a panoramic radiography by said another X-ray apparatus, said attribute information including apparatus type of said another X-ray apparatus, and said orbit of said X-ray CT apparatus for the panoramic radiography being different from an orbit of said another X-ray apparatus for the panoramic radiography; a display operation means having thereon a specific display area with which an X-ray image data of a panoramic image obtained by said X-ray CT apparatus or said X-ray image data taken from said another apparatus is shown as a scout view and designating an interested area on the displayed area; a coordinate processing means selecting one of converting regulations for a panoramic image obtained by said X-ray CT apparatus, and selecting another converting regulation for the panoramic image obtained by said another X-ray apparatus with reference to said attribute information corresponding to the type of X-ray apparatus, and converting a two-dimensional position of said designated interested area on said display area into a three-dimensional coordinate information based on said selected another converting regulation; and a position control means for relatively moving said object, to said X-ray generator and said X-ray detector, in order to execute the CT for said local region of said interested area, based on said three-dimensional coordinate information as converted.