Disclosed is a complementary metal oxide semiconductor (CMOS) image sensor. The image sensor comprises a first separation zone in a substrate, the first separation zone defining first and second pixel regions arranged in a first direction, the first separation zone including first parts substantially parallel extending in the first direction, and the substrate including a first active region vertically overlapping one of the first parts and a second active region vertically overlapping another of the first parts. The image sensor further comprises first and second photoelectric conversion devices arranged in the first direction on at least one of the first and second pixel regions in the substrate, and a source follower gate on the first active region of the substrate.