A semiconductor device including a substrate, a polysilicon semiconductor layer, and a conductive wire is provided. The polysilicon semiconductor layer is disposed on the substrate. The conductive wire is disposed on the substrate. The conductive wire contacts the polysilicon semiconductor layer through a contact portion. The polysilicon semiconductor layer and the contact portion of the conductive wire respectively have sides aligned with each other. The semiconductor device of the disclosure has good electrical connection, mitigated contact problems, improved reliability, reduced resistivity, increased driving capability, or improved display quality.