An image sensor includes first pixels and a first source follower transistor, which are disposed adjacent to each other in a first pixel area in a column direction, and second pixels and a second source follower transistor, which are formed in a second pixel area adjacent to the first pixel area in a row direction by the same number of the first pixels, wherein when the first pixels share the first source follower transistor and the second pixels share the second source follower transistor, while pixels selected from the same row are activated, the first source follower transistor and the second source follower transistor being activated are disposed so that locations thereof have a diagonal symmetry.