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 through use of architectural and addressing features. A principal feature lies in setting as a high reliability region a specific memory sector (first sector) among a plurality of memory sectors. Within the high reliability sector, two or more memory cells are written with the same data. During reading, the simultaneously written memory cells are read simultaneously, increasing current flow through the parallel current paths. This nonvolatile memory allows the size of the high reliability sector to be adjusted using signals supplied from external to the nonvolatile memory.