An image sensing device comprising a plurality of unit photosensing pixels to convert light into electrical signals, each unit photosensing pixel including a photosensor and a plurality of transistors to perform operations associated with the photosensor and a plurality of protection devices, each of which is coupled to any one of the plurality of transistors, wherein each of the plurality of protection devices includes a first region doped with a first type of conductive impurities, a second region doped with a second type of conductive impurities and surrounding the first region, and a third region doped with the first type of conductive impurities and surrounding the second region, wherein the first region includes a contact portion and a first well located below the contact portion, and wherein the contact portion has a higher doping density than the first well, and is coupled to any one of the plurality of transistors.