A semiconductor device includes at least a first wire pattern, a gate electrode, a semiconductor pattern, a gate insulating layer, and a first spacer. The first wire pattern is on a substrate and isolated from the substrate. The gate electrode surrounds and intersects the first wire pattern. The semiconductor pattern is on both sides of the first wire pattern, and the semiconductor pattern includes a portion which overlaps the first wire pattern. The gate insulating layer is disposed between the gate electrode and the first wire pattern, and the gate insulating layer surrounds the first wire pattern. The first spacer is between the first wire pattern and the substrate, and the first spacer is between the gate insulating layer and the semiconductor pattern.