PROBLEM TO BE SOLVED: To provide an intramedullary fixation system capable of mutually independently setting engagement modes of a plurality of shaft-like members without sacrificing operability during a surgery.SOLUTION: The intramedullary fixation system comprises: an intramedullary nail body 110 including a shaft hole 113, a first transverse hole 114, and a second transverse hole 115 a first engagement member 121A including a first engagement part 121b capable of protruding into the first transverse hole, and a through aperture 121c communicating to the second transverse hole a second engagement member 121B including a second engagement part 121k capable of protruding into the second transverse hole a movable operation member including a first positioning portion corresponding to the first engagement member and a second positioning portion corresponding to the second engagement member a first shaft-like member 10 inserted into the first transverse hole and a second shaft-like member 20 inserted into the second transverse hole and the through aperture.
