An endoscopically inserting surgical tool (1) is composed of an elongated flexible cord (3) to be passed through a tool guide channel (45) on an endoscope (40), and a tool action mechanism (2) mounted on a fore distal end of the flexible cord (3) to be projected out of the tool guide channel (45). The flexible cord (3) has such a length that, when the tool action mechanism (2) is projected out of a tool exit opening (46) at the end of the tool guide channel (45), a proximal end portion of the flexible cord (3) still remains outside and rearward of a tool entrance way (44) which is provided on a manipulating head grip (41) of the endoscope (40) as an approach to the tool guide channel (45). A proximal end portion of the flexible cord (3) is gripped in a rotary tool adjustor (50) which is manipulable to turn the tool action mechanism (2) clockwise or counterclockwise together with the flexible cord (3) in the tool guide channel (45) of the endoscope (40).
