An insertion tool of an intraocular lens permits the lens to be deformed while rotation of the lens in an insertion tube is effectively prevented. Upper and lower flat planes are formed to spread flatly over a length of a through hole in the insertion tube and the upper and lower flat planes are connected smoothly with right and left wall faces over the length of the through hole. The right and left wall faces have longitudinal linear portions extending substantially in parallel in a vertical direction on a proximal end opening side. With its radius of curvature decreasing gradually in a covered shape which becomes inwardly concave as it approaches a distal end opening the upper flat plane gradually approaches the lower flat plane, and a tapered portion having a reduced cross-sectional area is formed, thus obtaining the distal end opening of substantially oval shape.