Example embodiments disclose an image sensor capable of preventing or reducing image lag and a method of manufacturing the same. Example methods may include forming a gate insulating film and a gate conductive film doped with a first-conductive-type dopant on a semiconductor substrate; forming a transfer gate pattern by patterning the gate insulating film and the gate conductive film; and fabricating a transfer gate electrode by forming a first-conductive-type photodiode in the semiconductor substrate adjacent to one region of the transfer gate pattern, by forming a second-conductive-type photodiode on the first-conductive-type photodiode, and by forming a first-conductive-type floating diffusion region in the semiconductor substrate adjacent to the other region of the transfer gate pattern.