The present invention provides an image sensor and a fabricating method of the image sensor. The image sensor comprises: a first type epitaxial layer, a photodiode region, a first type well region, a gate region of a source follower transistor, and a first type implant isolation region. The first type well region is formed within the first type epitaxial layer with a first horizontal distance to the photodiode region and a vertical distance to a surface of the first type epitaxial layer. The gate region of a source follower transistor is formed on the surface of the first type epitaxial layer and above the first type well region, and has a second horizontal distance to the photodiode region. There is a distance between the first type implant isolation region and the first type well region as an anti-blooming path.