A radiofrequency switch device includes an insulation layer, a semiconductor layer, a gate structure, a first doped region, a second doped region, an epitaxial layer, a first silicide layer, and a second silicide layer. The semiconductor layer is disposed on the insulation layer. The gate structure is disposed on the semiconductor layer. The first doped region and the second doped region are disposed in the semiconductor layer at two opposite sides of the gate structure respectively. The epitaxial layer is disposed on the first doped region. The first silicide layer is disposed on the epitaxial layer. The second silicide layer is disposed in the second doped region.