A binding tool for documents or the like is provided which is capable of suppressing the height of protruded portions from a surface of a base portion thereby to expand a space thereabove, and which is also easy to manufacture and assemble. The binding tool includes a base portion (2) formed of a metal plate, rings (3) that are each mounted on the base portion so as to be selectively changed into a closed ring posture to bind documents or the like and an opened ring posture to open a part of a closed ring for insertion of the documents or the like, and a switching mechanism (5) that is mounted on the base portion and includes a switching lever (4) for switching the rings between the closed ring posture and the opened ring posture. The switching lever has a base end (41) and a free end (42), and a cam member (6) is provided on the base end of the switching member for adjusting the degree of opening/closing of each of the rings according to a rotated position of the free end. The cam member has a cam main body (61) and camshafts (62) that protrude from the cam main body, and bearing portions (25) are formed in the base portion. The bearing portions are each formed of an inner surface of a curved portion where a part of the base portion is curved to a front surface side thereof.