A semiconductor device includes an insulating substrate, a first semiconductor region configured of polysilicon formed on the insulating substrate, an insulating film laminated on the first semiconductor region, a contact hole formed in the insulating film and reaching the first semiconductor region, a second semiconductor region configured of an oxide semiconductor formed on the insulating film, a contact electrode configured of a conductive material and electrically connected to the first semiconductor region, where the conductive material is embedded in the contact hole. The insulating film contains a metallic element at an interface with the contact hole, where the metallic element forms the oxide semiconductor.