A nonvolatile memory capable of acting at each 1 bit and having a high integration density. A small-sized semiconductor device of multiple high functions having such nonvolatile memory. The nonvolatile memory is constructed to have a memory cell composed of two memory transistors so that it can realize a memory capacity of two times as large for a memory area as that of the full-function EEPROM of the prior art, in which the memory cell is composed of one memory transistor and one selection transistor, while retaining functions similar to those of the EEPROM. On the other hand, the small-sized semiconductor device of high functions or multiple functions is realized by forming the nonvolatile memory of the invention integrally with another semiconductor part over a substrate having an insulating surface.