A semiconductor device includes a substrate having a first surface on which an active region is disposed, and a second surface opposite the first surface, a buried conductive line extending in one direction and having a portion buried in the active region, an insulating portion covering the buried conductive line, a contact structure disposed on the insulating portion and connected to the buried conductive line, a through-hole extending from the second surface to the insulating portion and exposing the buried portion of the buried conductive line, an insulating isolation film disposed on a side surface of the buried conductive line and exposing a bottom surface of the buried portion and a side surface adjacent to the bottom surface, a through-via contacting the bottom surface and the adjacent side surface of the buried conductive line, an insulating liner surrounding the through-via.