A medical treatment tool includes a bendable tube configured to be inserted into a body of a patient; an operating body disposed in the bendable tube and configured to cause bending of the bendable tube, the operating body including: a plurality of divided members that are divided from each other along axially extending edges of adjacent divided members, portions of the divided members forming a tubular structure, and an annular connecting portion, an outer surface of the annular connecting portion being continuous with outer surfaces of the divided members; and a cylindrical member located inside the operating body. Each divided member includes at least one cutout portion formed between the tubular structure and the annular connecting portion. The cylindrical member is in contact with inner surfaces of the divided members.