An image sensor includes a first semiconductor layer having a first semiconductor region and a first insulating region, and a second semiconductor layer under the first semiconductor layer including a second semiconductor region and a second insulating region. The first semiconductor layer includes a first transistor having first source or drain regions in the first semiconductor region and a first gate electrode in the first insulating region, a contact wiring, a first wiring layer electrically connecting the contact wiring and the first transistor, and a first junction region electrically connected to the first wiring layer. The second semiconductor layer includes a second transistor having second source or drain regions in the second semiconductor region and a second gate electrode in the second insulating region, a second wiring layer electrically connecting the contact wiring and the second transistor, and a second junction region electrically connected to the second wiring layer.