PROBLEM TO BE SOLVED: To prevent a pin for intraosseous insertion and fixation from coming off a treated region by coupling a tension band wire and the pins for intraosseous insertion and fixation.SOLUTION: An instrument used in a tension band wiring method being a fracture therapy or ostheosynthesis includes: the tension band wire 44 the pin 43 for intraosseous insertion and fixation and the coupler 100 for fixing and keeping the tension band wire 44 and the proximal ends 430 of the pins 43 for intraosseous insertion and fixation.