The present invention discloses a semiconductor device and a method of fabricating the same. According to an exemplary embodiment of the present embodiment, a semiconductor device is provided as follows. An active fin protrudes from a substrate, extending in a direction. A gate structure crosses a first region of the active fin. A source/drain is disposed on a second region of the active fin. The source/drain includes upper surfaces and vertical side surfaces. The vertical side surfaces are in substantially parallel with side surfaces of the active fin.