A semiconductor device having a gate-all-around structure includes a first fin pattern and a second fin pattern separated by a first trench and extending in a first direction, a first nanosheet on the first fin pattern, a second nanosheet on the second fin pattern, a first fin liner extending along at least a portion of a sidewall and a bottom surface of the first trench, a first field insulation layer disposed on the first fin liner and filling a portion of the first trench, and a first gate structure overlapping an end portion of the first fin pattern and including a first gate spacer. A height from the bottom surface of the first trench to a lower surface of the first gate spacer is greater than a height from the bottom surface of the first trench to an upper surface of the first field insulation layer.