This endoscope system comprises image pickup means having an image pickup device, illumination light ejecting means having an illumination light ejection portion, an endoscope having an insertion portion and having an illumination light incident portion and an optical image ejection portion for ejecting subject light, a first connection portion for attaching the endoscope to the image pickup means so that the subject light can be captured, a second connection portion for attaching the endoscope to the illumination light ejecting means so that the light from the illumination light ejection portion can enter the illumination light incident portion, an optical path having a first adapter connection portion attachable to the first connection portion and a second adapter connection portion attachable to the second connection portion for capturing the subject image, and an adapter having an illumination optical system for guiding the illumination light to the image pickup region.
