There is provided a semiconductor device including a semiconductor substrate (10), a high concentration diffusion region (22) formed within the semiconductor substrate (10), a first low concentration diffusion region (24) that has a lower impurity concentration than the high concentration diffusion region (22) and is provided under the high concentration diffusion region (22), and a bit line(30) that includes the high concentration diffusion region (22) and the first low concentration diffusion region (24) and serves as a source region and a drain region, and a manufacturing method therefor. Reduction of source-drain breakdown voltage of the transistor is suppressed, and a low-resistance bit line can be formed. Thus, a semiconductor device that can miniaturize memory cells and a manufacturing method therefor can be provided.