PROBLEM TO BE SOLVED: To prevent an output image from becoming dark in special light image observation such as a narrow band light observation.SOLUTION: An endoscope system includes an endoscope 10, a processor 11, and a monitor 12. The processor 11 has a lamp 21, and normal light emitted from the lamp 21 is radiated from a distal end part 10A of the endoscope 10 to a subject through a filter 27. The filter 27 generates special light by transmitting a part of a wavelength band of the normal light to irradiate the subject with the special light. When the subject is irradiated with the special light, an emission light quantity of the lamp 21 is controlled, by a lamp control part 22, so as to be relatively large in an odd-numbered field and be relatively small in an even-numbered field. Special light image data obtained in the odd-numbered field is outputted to the monitor 12 continuously as special light images of the odd-numbered/even-numbered fields.
