A resistance-integrated gas sensor is provided, including a substrate, a first metal oxide layer, an insulating layer, a contact metal layer, a contact hole, a second metal oxide layer, and an interdigitated electrode layer. The first metal oxide layer is disposed in the substrate. The insulating layer is disposed on the substrate and the first metal oxide layer. The contact metal layer and the contact hole are disposed in the insulating layer. The second metal oxide layer is disposed on the insulating layer. A portion of the interdigitated electrode layer is disposed on the insulating layer, and another portion is disposed in the second metal oxide layer. The contact metal layer and the contact hole connect the first metal oxide layer and the interdigitated electrode layer.