A femur fixation apparatus capable of firmly fixing in place an anti-rotation member, which includes an intramedullary nail, an anti-rotation pin configured to be inserted through the intramedullary nail, and an adjuster fitted in the intramedullary nail. The adjuster includes a rotation part and a sliding part. The rotation part is rotatably and threadedly engaged in the intramedullary nail and rotatably connected to the upper end of the sliding part. The sliding part is formed with a space through which the anti-rotation pin is inserted. An urging member extends from a side wall of the space into the space. When the rotation part is rotated in a predetermined direction relative to the intramedullary nail, then the adjuster moves downward, and the urging member presses downward and fixes in place the anti-rotation pin.
