Nonvolatile semiconductor memory device

A nonvolatile memory increases the number of times that data can be written and the length of time that data can be stored. A feature of the memory sets as a high reliability region a specific memory sector (for example, "0000" to "00FF") among a plurality of memory sectors. Within the high reliability sector, two or more memory cells are simultaneously written with the same data. During reading, the simultaneously written memory cells are read simultaneously, increasing current flow through the parallel current paths.