A flash memory based file memory device built in an information processing apparatus enables fast file access. The file memory device is provided with a parallel arrangement of memory element groups having a unit erasure block size greater than the data bus width of the memory device and a data access width smaller than the data bus, a file division unit for dividing file data that consists of one or more unit storage data blocks into combined blocks that consists of a combination of arbitrary unit storage data blocks, a data distribution unit for combining arbitrarily data on the data bus in terms of the unit data size equal to the data access width and making the combined data correspondent to an arbitrary combination of memory element groups equal in number to the unit size data, and a control unit for controlling the data distribution unit such that each combined block is stored in the file memory device by being correspondent to one of the arbitrary combinations of memory element groups.