A semiconductor integrated circuit comprises a semiconductor substrate of a first conductivity type, at least one electrically erasable floating gate type semiconductor non-volatile memory transistor disposed on a surface of the semiconductor substrate, a well region of a second conductivity type formed in the surface of the semiconductor substrate, and a program voltage switching transistor of the first conductivity type disposed in the well region. A field insulation film is disposed on the surface of the semiconductor substrate. A field dope region of the first conductivity type is provided beneath the field insulation film. The field dope region preferably has an impurity concentration higher than an impurity concentration of the semiconductor substrate. By this construction, current leakage is prevented at the time when a high voltage occurs such as, for example, when performing a writing operation with respect to EEPROM.