A semiconductor device and a method for manufacturing the semiconductor device are provided. The semiconductor device includes an insulating layer, a semiconductor layer, a plurality of isolation structures, a transistor, a first contact, a plurality of silicide layers, and a protective layer. The semiconductor layer is disposed on a front side of the insulating layer. The plurality of isolation structures are disposed in the semiconductor layer. The transistor is disposed on the semiconductor layer. The first contact is disposed beside the transistor and passes through one of the plurality of isolation structures and the insulating layer therebelow. The plurality of silicide layers are respectively disposed on a bottom surface of the first contact and disposed on a source, a drain, and a gate of the transistor. The protective layer is disposed between the first contact and the insulating layer.