A first device region is formed in a first well region provided on a semiconductor substrate and a second device region is formed in a second well region, both of which are separated by a field oxidation film, a memory transistor for writing a program is provided in the first device region, an address transistor controlling the writing is provided in the second device region, and a source region of the address transistor and a drain region of the memory transistor are connected by an interconnecting metal to structure a semiconductor nonvolatile memory device which can electrically perform writing only once.