A data processing apparatus and method are provided for a flash memory, wherein the data processing apparatus and method can easily determine whether data stored in the flash memory is valid. The data processing apparatus for a flash memory includes a user request unit which issues a request for performing a data operation on a predetermined logical address, a conversion unit which converts the predetermined logical address into a physical address, and a control unit which performs the data operation on the physical address and records inverted data of data written to the predetermined logical address in an index area to indicate whether the data written to the predetermined logical address is valid.