PROBLEM TO BE SOLVED: To provide an electronic endoscope system by which a treatment position can be easily specified while reducing a load on a subject during treatment by PDT.SOLUTION: An electronic shutter is opened to accumulate signal charge in a partial period of treatment light irradiation to capture an image by ordinary light. When a prescribed treatment light irradiation period elapses from starting the irradiation of treatment light, the irradiation of the treatment light is stopped. When the irradiation of the treatment light is stopped, the electronic shutter is opened to accumulate signal charge in a signal charge accumulation period from stopping the treatment light irradiation to finishing one frame period, and an image is captured by ordinary light. By capturing an image by ordinary light during treatment light irradiation, an irradiation position of the treatment light can be confirmed and the circumference of a treatment position can be observed by capturing an image by ordinary light thereafter.
