A semiconductor device comprising a first transistor, a second insulating film, a conductive film, and a capacitor is provided. The first transistor comprises a first oxide semiconductor film, a gate insulating film over the first oxide semiconductor film, and a gate electrode over the gate insulating film. The second insulating film is provided over the gate electrode. The conductive film is electrically connected to the first oxide semiconductor film. The capacitor comprises a second oxide semiconductor film, the second insulating film over the second oxide semiconductor film, and the conductive film over the second insulating film. The first oxide semiconductor film comprises a first region and a second region. Each of a carrier density of the second region and a carrier density of the second oxide semiconductor film is higher than a carrier density of the first region.