1. An apparatus for preoperative planning of an artificial knee joint replacement operation, comprising: means for inputting images which inputs two-dimensional tomographic images of the lower limb including the knee joint; means for reconstructing images which reconstructs three-dimensional images of the femur and tibia from the images input by the means for inputting images; means for determining femur side artificial joint which determines the artificial joint to be replaced from the three-dimensional images of the knee joint of the femur obtained by the means for reconstructing the images; means for determining tibia side artificial joint which determines the artificial joint to be replaced from the three-dimensional images of the knee joint of the tibia obtained by the means for reconstructing the images; and means for parameter determination which determines various parameters used in artificial knee joint replacement using an alignment rod in the marrow which is inserted into the femur based on the artificial joint determined by the means for determining femur side artificial joint and reference points of the knee joint.