An electronic endoscope comprises a storage device wherein are disposed a plurality of storage regions which store white balance setting values which a processor provides and which correspond to an internal light source and an external light source. The processor comprises a first light guide connection sensing unit which senses whether a light guide of the electronic endoscope is connected. The external light source comprises: a second light guide connection sensing unit which senses whether the light guide is connected thereto and a sensing result transmission unit which transmits the sensing result of the second light guide connection sensing unit to the processor. The processor further comprises: a sensing result receiving unit which receives the sensing result of the second light guide connection sensing unit which is transmitted from the sensing result transmission unit a used light source assessment unit which assesses a light source in use on the basis of the sensing results of the first and second light guide connection sensing units a white balance setting value acquisition unit which acquires the white balance setting value which corresponds to the assessed light source in use and a color tone adjustment unit which uses the white balance setting value to carry out a color tone adjustment of image data.
