A data generalization apparatus for generalizing attribute values, the data generalization apparatus comprising: a rearrangement unit that rearranges the attribute values in a secondary storage device in accordance with an order of arrangement of the attribute values in a generalization hierarchy in the secondary storage device; characterized in that the data generalization apparatus further comprises: an attribute value retrieval unit that retrieves some of the rearranged attribute values from the secondary storage device into a primary storage device; a generalization hierarchy retrieval unit that retrieves a portion of the generalization hierarchy from the secondary storage device into the primary storage device, the portion corresponding to the attribute values to be processed among the attribute values retrieved into the primary storage device; a generalization processing unit that executes generalization processing based on the attribute values retrieved into the primary storage device and the generalization hierarchy retrieved into the primary storage device; and a re-rearrangement unit that moves the attribute values after the generalization processing to the secondary storage device and rearranges them into an original order. a rearrangement unit that rearranges the attribute values in a secondary storage device in accordance with an order of arrangement of the attribute values in a generalization hierarchy in the secondary storage device; characterized in that the data generalization apparatus further comprises: an attribute value retrieval unit that retrieves some of the rearranged attribute values from the secondary storage device into a primary storage device; a generalization hierarchy retrieval unit that retrieves a portion of the generalization hierarchy from the secondary storage device into the primary storage device, the portion corresponding to the attribute values to be processed among the attribute values retrieved into the primary storage device; a generalization processing unit that executes generalization processing based on the attribute values retrieved into the primary storage device and the generalization hierarchy retrieved into the primary storage device; and a re-rearrangement unit that moves the attribute values after the generalization processing to the secondary storage device and rearranges them into an original order. an attribute value retrieval unit that retrieves some of the rearranged attribute values from the secondary storage device into a primary storage device; a generalization hierarchy retrieval unit that retrieves a portion of the generalization hierarchy from the secondary storage device into the primary storage device, the portion corresponding to the attribute values to be processed among the attribute values retrieved into the primary storage device; a generalization processing unit that executes generalization processing based on the attribute values retrieved into the primary storage device and the generalization hierarchy retrieved into the primary storage device; and a re-rearrangement unit that moves the attribute values after the generalization processing to the secondary storage device and rearranges them into an original order.