A method for fabricating a semiconductor device includes the steps of first forming an active device having a gate structure and a source/drain region on a substrate, forming an interlayer dielectric (ILD) layer on the active device, removing part of the ILD layer to form a contact hole on the active device without exposing the active device and the bottom surface of the contact hole is higher than a top surface of the gate structure, and then forming a metal layer in the contact holt to form a floating contact plug.