A semiconductor device including active regions defined in a semiconductor substrate to be non-parallel with a first direction and a second direction which are perpendicular to each other, word lines intersecting active regions and extending in first directions to be spaced apart from each other in the second direction, bit lines crossing over word lines and extending in second directions to be spaced apart from each other in the first direction, first impurity regions disposed in respective ones of central portions of active regions to non-overlap with the word lines, second impurity regions disposed in both ends of each of the active regions to non-overlap with the word lines, and bit line contact plugs disposed between the first impurity regions and the bit lines. The bit line contact plugs having longish shapes including major axes substantially parallel with the second direction and minor axes substantially parallel with the first direction.