Abstract: De-identification device for automatically configuring a general hierarchy tree of attribute values of identity information. The provided de-identification device quantitatively evaluates the amount of information which is lost when generalizing an attribute value, and can thereby automatically assess priorities between de-identified data and between data that is being de-identified. Information of each person includes attribute values of the person for a plurality of attributes. De-identification is achieved by obfuscating the attribute values, and a structure in which attribute values to be obfuscated are expressed in a tree structure according to the level of obfuscation is called a general hierarchy tree. The disclosed identity information de-identification device achieves automatic configuration by configuring a tree using frequency information of attribute values.