PURPOSE: To effectively enlarge the FOV of an image reconfiguration area without enlarging a detector by averaging the data being not an over-size by projection integration, and embedding over-size data from other data and averaged data.

CONSTITUTION: After a data collection is started, whether a body to be examined is an over-size against X-ray irradiation in its view or not is checked, unless it is an over-size, '1' is added to the number (j) of its view, projective integration Sj of data of the (j) view is derived, and an average value Sj of the integral value concerned S1 is derived. Subsequently, the number of the data of an over-size is set to '1', the number nk of its view is registered by an (i) number, it is set as new (k) by adding k=1, an integral value Snk of over-size data in the nk view is derived, and by subtracting the integral value concerned Snk from the average value Sj of the whole integral value, an area S2 of an FOV to be extended is derived, and by adding the data concerned S2 to the average value Sj between (x) channels and embedding the data, it is possible to have the data for covering the whole body to be examined, and an image of the extended FOV is obtained.