A method and structure of manufacture of mask ROM device is provided. Firstly, a semiconductor structure is provided that comprises a first dielectric layer, a plurality of buried bit lines and a plurality of code areas, wherein each of the code areas is placed between two buried bit lines. Next, a second dielectric layer having a plurality of contact plugs is formed on the semiconductor structure, wherein the contact plug comprises a second dielectric layer and a first glue layer, furthermore; the first glue layer is placed on the side-wall and bottom of the contact plugs. In addition, the contact plugs filled with the first metal layer. Then, a second glue layer, a second metal layer and a pad layer having an opening pattern are respectively formed on the second dielectric layer and contact plug. Thus, the processes of the present invention can improve the stability and accuracy in the electricity of the mask ROM device.