Contact structures, FinFET devices and methods of forming the same are disclosed. One of the contact structures includes a source/drain region, a mask layer, a connector and a shielding pattern. The source/drain region is between two gate stacks. A mask layer is over the gate stacks and has an opening corresponding to the source/drain region. The connector is electrically connected to the source/drain region, penetrates through the opening of the mask layer and protrudes above and below the mask layer. The shielding pattern is between the mask layer and the connector and in physical contact with the mask layer.