PURPOSE: To accurately carryout alignment at high speed.

CONSTITUTION: Reference correspondent points 40A-40D are set on a radiograph, and template areas 41A-41D are set with these reference correspondent points as centers. The correspondent points are set by executing template matching in any area on the other radiograph while using these template areas 41A-41D. Next, affin transformation is executed to match the correspondent points with the reference correspondent points 40A-40D, new correspondent points are set by moving the template areas 41A-41D inside any area smaller than the area on the other radiograph and the new correspondent points are matched with the reference correspondent points 40A-40D by the expression of affin transformation so that the position of the radiograph can be matched with that of the other radiograph.