Provided is a data processing system having a processor and a storage apparatus coupled to the processor, wherein: the storage apparatus holds a plurality of encrypted data that are generated by encrypting a plurality of plain text data, and a plurality of encrypted queries for retrieving the plurality of encrypted data directly in an encrypted state; and the processor retrieves each of the encrypted data using each of the encrypted queries and thereby calculates the number of appearances of encrypted data that are retrieved using each of the encrypted queries, changes at least two of the plurality of encrypted data on the basis of the number of appearances of encrypted data that are retrieved using each of the encrypted queries so that predetermined anonymity is satisfied, and outputs a plurality of encrypted data.