An image sensor is provided to include image pixels and phase difference detection pixels. The image pixels may include image photodiodes formed in a substrate; color filters formed over the substrate and vertically overlapping with the image photodiodes; and image micro lenses over the color filters. The phase difference detection pixels may include phase difference detection photodiodes formed in the substrate; transmitting layers formed over the substrate and vertically overlapping with the phase difference detection photodiodes; guide patterns formed between the substrate and the transmitting layers; and phase difference detection micro lenses over the transmitting layers. The transmitting layers may have a refractive index lower than the color filters and the phase difference detection micro lenses.