A semiconductor device includes a substrate including a cell array region having a first active region and a peripheral circuit region having a second active region, an insulating layer pattern on the substrate and including a hole corresponding with the first active region, a DC conductive pattern in the hole, connected to the first active region, and buried in the substrate, a bit line connected to the DC conductive pattern and including a first bit line conductive pattern contacting the DC conductive pattern and covering a top surface of the insulating layer pattern, and a gate insulating layer and a gate electrode structure on the second active region, the gate electrode structure including a gate conductive pattern and a first gate electrode conductive pattern, the first gate electrode conductive pattern including a same material as the first bit line conductive pattern.