A semiconductor device includes a substrate having a first active region; first and second gate electrodes disposed on the first active region; first, second and third impurity regions disposed in the first active region; first, second and third active contacts disposed on and connected to the first, second and third impurity regions; a first power line electrically connected to the first impurity region through the first active contact; and a first bit line electrically connected to the second and third impurity regions through the second and third active contacts. The first gate electrode and the first and second impurity regions form a first transistor of a first memory cell. The second gate electrode and the second and third impurity regions form a second transistor of a second memory cell. The second impurity region is a drain of the first and second transistors of the first and second memory cells.