A semiconductor device and a method of fabricating the same are provided. The semiconductor device comprises a first multi-channel active pattern which is defined by a field insulating layer, extends along a first direction, and includes a first portion and a second portion; a gate electrode which extends along a second direction different from the first direction and is formed on the first portion; and a first source/drain region which is formed around the second portion protruding further upward than a top surface of the field insulating layer and contacts the field insulating layer, wherein the second portion is disposed on both sides of the first portion in the first direction and is more recessed than the first portion, a top surface of the first portion and a top surface of the second portion protrude further upward than the top surface of the field insulating layer, and a profile of sidewalls of the second portion is continuous.