An image sensor includes a substrate having a first conductivity type, a first charge accumulation region disposed in the substrate and having a second conductivity type, a second charge accumulation region connected with the first charge accumulation region, having the second conductivity type and extending downward from an edge of the first charge accumulation region, a pinning region disposed on the first charge accumulation region and having the first conductivity type, a floating diffusion region spaced laterally from the pinning region, a channel region disposed between the pinning region and the floating diffusion region, and a gate structure disposed on the channel region.