A semiconductor device and method of manufacturing the same. The method includes: defining a first active area and a second active area on a substrate, the first and second active areas being in a line form, forming a first main trench and a second main trench on the substrate, forming a first sub-trench and a second sub-trench in bottoms of the first and second main trenches, respectively, forming a buried insulation layer filling the first and second sub-trenches, partially exposing the substrate at an area where the first active area crosses with the first sub-trench and an area where the second active area crosses with the second sub-trench and forming the first buried bit line and the second buried bit line on the buried insulation layer, and the first and second buried bit lines being extended in parallel to each other.