PROBLEM TO BE SOLVED: To simply obtain a fixation force of a shaft-like member to be inserted into a transverse hole provided on a body without sacrificing operability in a surgical operation.SOLUTION: An intramedullary fixation system includes: an intramedullary nail body 110 having an extended shape as a whole, and including a shaft hole 113 extending in a shaft line 100X direction at least on one end side, and at least one transverse hole 114 penetrating in a direction crossing the shaft line direction and communicated with the shaft hole an engaging member 121 rotatably arranged around the shaft line in the inside of the shaft hole, and including a through opening part 121c communicated with the transverse hole rotation operation means 125 and 118 forming the engaging member on the intramedullary nail body in a rotatively operable manner around the shaft line and a shaft-like member 20 inserted into the transverse hole and the through opening part. The shaft-like member is pinched between the hole inner edge of the transverse hole and the opening inner edge of the through opening part to be fastened and held, by rotating the engaging member around the shaft line by the rotation operation means in a state that the shaft-like member is inserted into the transverse hole and the through opening part.
