A semiconductor integrated circuit with a nonvolatile memory has a plurality of nonvolatile data memory elements arranged in a matrix and a means for reading data from the memory elements in accordance with an address signal which specifies a position in the matrix. A protecting data memory element for storing at least one-bit protection data is disposed in the matrix. Whether operations such as a programming (i.e., writing), erasing or reading with respect to the data memory elements will be allowed or inhibited is determined in accordance with the contents of the protecting data memory element. In other words, data security in an arbitrary area of the matrix can be accomplished based on the content of the protecting data memory element.