Abstract: In an X-ROM memory device both metal changeable GND lines and polysilicon changeable GND lines are used as a changeable GND line. The metal changeable GND lines are respectively located on both sides of an array of a fixed number of polysilicon changeable GND lines. Odd polysilicon changeable GND lines are commonly connected to one metal changeable GND line through a predetermined polysilicon line, and even polysilicon changeable GND lines are commonly connected to the other metal changeable GND line through another predetermined polysilicon line. Each of the metal changeable GND lines are then connected to a GND terminal through the driving cell transistors.