An image sensor including a semiconductor layer including a plurality of unit pixels each including a photoelectric conversion device and read devices; and an insulating layer including a light-shielding pattern defining a light-receiving region and a light-shielding region of the semiconductor layer, the insulating layer covering one surface of the semiconductor layer. The semiconductor layer further includes a potential drain region formed adjacent to an interface between the semiconductor layer and an insulating layer in the light-shielding region, wherein electrons generated due to defects occurring at the interface are accumulated in the potential drain region. At least one of the unit pixels in the light-shielding region provides a drain path for draining the electrons accumulated in the potential drain region.