PURPOSE: To facilitate rotation of a turn buckle and to facilitate mounting and demounting of the turn buckle.

CONSTITUTION: A lower jaw guide 2a the upper surface of which is formed in an arcuate state is formed to the tip of a handle 2. Two L-shaped coupling members 4 are fixed in front of the handle 2, an upper jaw guide 3 formed approximately in a C-shape is rotatably mounted on the protrusion parts 4a of the coupling members 4, and pressed and energized in a counterclockwise direction through the force of a spring 6. An engaging surface 8 engaged with a turn buckle is formed at the tip of the upper jaw guide 3. Thus, when a handle 2 is rotated in a forward direction, the turn buckle is rotated integrally with a rotary auxiliary tool 1 for the turn buckle. When the handle 2 is rotated in a reverse direction, only the rotary auxiliary tool 1 for a turn buckle is raced. The turn buckle is easily mounted in and demounted from an opening 9 through rotation of the upper jaw guide 3.