A semiconductor device includes a gate pattern crossing over a substrate, the gate pattern including a gate insulating layer, a gate electrode, and a gate capping pattern sequentially stacked on the substrate, a gate spacer covering a sidewall of the gate pattern, a source/drain pattern on the substrate, the source/drain pattern being adjacent to the sidewall of the gate pattern, a contact pad on the source/drain pattern, a top surface of the contact pad being lower than a top surface of the gate electrode, a source/drain contact plug on the contact pad, and a protection spacer between the gate spacer and the source/drain contact plug, the protection spacer having a ring shape enclosing the source/drain contact plug.