1. A semiconductor memory device comprising: a unit data storage section configured by one or more data storage elements; and a data protection mechanism for inhibiting programming of data into the unit data storage section, wherein data stored in the unit data storage section is, after erased, formed into a specific erasure data pattern, and the data protection mechanism inhibits programming of data into the unit data storage section when the data stored in the unit data storage section is not in the erasure data pattern.