Patent ID: 8369151

Claim:
A nonvolatile semiconductor memory device comprising: a memory cell array including regular memory cells that are capable of switching between a first data storage state and a second data storage state by electric rewriting, and permanent memory cells that are not to be electrically rewritten and are fixed in a third data storage state that is read as the same logic level data as the first storage state; and a control circuit configured to control data rewriting into the memory cell array, data holding in the memory cell array, and data reading from the memory cell array, data to be written into the memory cell array being stored in at least one of the regular memory cells and at least one of the permanent memory cells in the memory cell array, the control circuit operative to rewrite at least one of the regular memory cells from the second data storage state to the first data storage state at the time of data holding, the control circuit operative to perform a reading operation after rewriting the regular memory cells from the first data storage state to the second data storage state at the time of data reading.