PROBLEM TO BE SOLVED: To provide an electronic endoscope system capable of obtaining sufficiently bright images without affecting observation with special light even when the system is in a distant view observation condition in which light quantity is short.SOLUTION: In a close view observation mode, image pickup is executed by irradiating a body cavity with a first blue narrow band light Bn1. An exposure quantity is detected from image pickup signals obtained by the image pickup. If the exposure quantity is less than a predetermined value, switching is made from the close view observation mode to a distant view observation mode. In the distant view observation mode, the image pickup is executed by irradiating the body cavity with a second blue narrow band light Bn2 obtained by increasing only the light quantity of a short wavelength without increasing the light quantity of a long wavelength from a central wavelength in the first blue narrow band light. As described above, since the second blue narrow band light Bn2 has a half value width wider than that of the first blue narrow band light Bn1, light quantity shortage in the distant view observation can be solved without affecting special light observation.
