PURPOSE: To reduce a false image expanding in a space by a method wherein projection data is generated with a compression processing covering a false image too to extract a false image component identifying the shape thereof and a restoration is performed by enlargement after an image reconstruction.

CONSTITUTION: An image data compression processor RDCT performs a compression processing of image data processed for extraction with an extraction processor PKUP. A projection data generator PRJ generates projection data for all necessary directions. A shape identifier DET performs a judgment of conditions by a formula to determine the presence of a false image. When the false image is found, a false image component generator APRJ determines projection data for generating the false images by computation to extract and generate the false image component. An image reconstructor RECON performs an image reconstruction of the false image. An image data enlargement processor EXTD performs an image enlargement for the false image reconstructed to be restored to the original data size. An image subtraction processor SIMAG subtracts the false image from the original image to obtain an image cleared of the false image.