An artificial hip joint stem is used to replace the damaged femoral head or acetabulum and includes a stem body having a head fixing part, which fixes a head, and an operating space horizontally opened at the upper side thereof. A head insertion hole connects to the operating space. A screw part is inserted into the head insertion hole. An operation converting part is inserted into the operating space to vertically move by the screw part when the operation converting part is connected to the screw part. A fixing bracket is inserted into the operating space such that the screw part is fixed to rotate without changing the depth thereof. A variable operating part is inserted into a supporting surface of the stem body to adjust a horizontal width by means of the operation converting part. A movable pin fixes the variable operating part to the operation converting part.
