A new through-hole programmed MASK ROM cell which is suitable for 1Mbit high speed MASK ROM with short turn around time in programming processes, and small cell size is descrived. The memory cell is implemented by NOR gate type which is most suitable for high speed MASK ROM. The new memory cell is successfully applied to 1Mbit MASK ROM with double polysilicon P-well C-MOS technology. A new structure and a new fabrication processes of the device element are also described.