The present invention relates to a side-view accessory of an endoscope, which is used to be fitted on an endoscope. The side-view accessory of an endoscope comprises a sleeve which is fitted in the endoscope and has an opening and a first and a second through holes, a reflecting mirror received within the sleeve and corresponding to the first through hole, a side light source received within the sleeve and corresponding to the second through hole, and a power source received within the sleeve and electrically connected with the side light source. The side light source has a light exiting surface facing the second through hole. The side-view accessories of an endoscope according to the present invention additionally provides a side light source to illuminate the inspection region on the side of the sleeve, so as to enhance the clarity of the captured images.
