Dark current caused by a crystalline defect in an interfacial surface of a device isolating layer is prevented according to an image sensor and a method of manufacturing the same. A first device isolating layer adjacent to a photodiode disposed on an upper surface of a semiconductor substrate protrudes from the semiconductor substrate. A side surface of the first device isolating layer is covered by a first spacer with a refractivity greater than that of the first device isolating layer. The photodiode is insulated by the device isolating layer protruding from the semiconductor substrate to prevent the dark current. By forming the spacer on the sidewall of the device isolating layer to attain total reflection, efficiency of light incident to the photodiode is improved.