A data processing device includes a memory interface (I/F) unit and a control unit. When accessing a data storage device such as a memory card having a built-in flash memory, the data processing device sets a block permission table (BPT) as an access permission table in the memory I/F unit, whereby only when the BPT permits a process to be executed does the memory I/F unit access the storage device, and the memory I/F unit does not execute a process when it is out of an allowable range. Regardless of a process type performed by the control unit and a command type, the memory I/F unit always accesses the storage device in accordance with the BPT set in the memory I/F unit. This effectively prevents the rewriting of data in rewrite-prevented recording media.