A semiconductor device having a high and stable operating voltage and a method of manufacturing the same, the semiconductor device including: a substrate having an active region including a channel region; a gate insulating layer that covers a top surface of the active region; a gate electrode that covers the gate insulating layer on the top surface of the active region; buried insulating patterns in the channel region of the active region at a lower side of the gate electrode and spaced apart from a top surface of the substrate; and a pair of source/drain regions in the substrate at both sides of each of the buried insulating patterns and extending from the top surface of the substrate to a level lower than that of each of the buried insulating patterns.