A semiconductor device includes: an active region defined by a device isolation layer formed in a substrate; a word line configured to cross the active region, the word line extending in a first direction and being formed in the substrate; a bit line extending in a second direction perpendicular to the first direction on the word line; a first contact connecting the bit line to the active region; a first mask for forming the active region, the first mask being formed on the active region; and a second mask of which a height of a top surface thereof is greater than a height of a top surface of the active region, the second mask covering the word line, wherein the active region has a bar shape that extends to form an acute angle with respect to the first direction.