A memory (1) in a non contact type IC card (100) includes a data protection region (B2) storing data requiring security and an region (B1) storing other data. A main control circuit (2) generates data to be stored and designates a location for data storage in the region (B1) or the data protection region (B2) according to a content of the data. An address non selecting circuit (4) selects whether the generated data is to be written into the location in the data protection region (B2) designated by the main control circuit (2) according to a state of a state setting circuit (3).