There are provided a semiconductor device and a fabrication method therefor including an ONO film (18) formed on a semiconductor substrate (10), a word line (24) formed on the ONO film (18), a bit line (20) formed in the semiconductor substrate (10), and a conductive layer (32) that is in contact with the bit line (20), runs in a length direction of the bit line (20), and includes a polysilicon layer or a metal layer. In accordance with the present invention, a semiconductor device and a fabrication method therefor are provided wherein degradation of the writing and erasing characteristics and degradation of the transistor characteristics such as a junction leakage are suppressed, and the bit line resistance is decreased.