The invention provides a manufacturing method of an image sensor, which comprises the following steps of: providing a semiconductor substrate with an insulating buried layer; selecting a photosensitive diode region of the image sensor, sequentially etching a semiconductor layer on a top layer and an insulating layer till exposing the surface of a supporting substrate; carrying out ion implantation and diffusion on the exposed supporting substrate to form an isolation area and an encapsulated well in the isolation area; forming a first doping area on the well region, leaving a space for interconnection between the first doping area and the well region; and manufacturing a signal readout circuit. Accordingly, the invention also provides an image sensor; a heavy doped isolation region of thephotosensitive diode region is encircled; a deeper depletion region can be generated through the isolation area; and the isolation area increases the light absorption efficiency and meanwhile isolates an electron hole irradiated and generated in the supporting substrate and increases the anti-radiation performance of the electron hole.