A medical treatment tool (10) includes a retractor main body (30) and a converter (20). The retractor main body (30) forms a cylindrical shape and is placed in an incision. The converter (20) is detachably installed on an opening end (32) of the retractor main body (30) and closes the opening end (32). Ports (22a) to (22d) through which treatment tools are respectively inserted into the retractor main body (30) are provided in a plurality of sites of the converter (20). The converter (20) can be installed on the opening end (32) at an installation angle which is selected from a plurality of angles. The positional relationships of the ports (22a) to (22d) with respect to the retractor main body (30) when the converter (20) is installed on the opening end (32) at the respective installation angles become different from each other.