| 摘要 |
A semiconductor storage device having a memory cell using threshold voltage difference to record data is provided to prevent read operation error due to indistinctness of threshold voltage without widening a threshold voltage window, by increasing a read voltage margin for the distribution of the threshold voltage. A plurality of memory cells store data by using a threshold voltage difference. At least one reference memory cell stores data indicating the state of the corresponding memory cell by using the threshold voltage difference. A control circuit(11) determines a read voltage on the basis of data stored in the memory cell and the reference memory cell corresponding to the memory cell. A read part(50) reads the memory cell by using the determined read voltage. A write part(50) writes data indicating that a memory cell for writing is in a write state, into the reference memory cell corresponding to the memory cell for writing, when the memory cell is already written.
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