1. An apparatus for preoperative planning of an artificial knee joint replacement operation, comprising: means for selecting images which accepts selection of a plurality of preliminarily input three-dimensional images of a femur and a tibia constructed from two-dimensional tomographic images of the lower limb including the knee joint; means for installing a femur side artificial joint which accepts selection of the artificial joint to be replaced and input of an installation position of the artificial joint to be replaced from the three-dimensional images of the knee joint of the femur obtained by the means for selecting the images, by using a plurality of preliminarily input three-dimensional images of the artificial joint; means for installing a tibia side artificial joint which accepts selection of the artificial joint to be replaced and input of an installation position of the artificial joint to be replaced from the three-dimensional images of the knee joint of the tibia obtained by the means for selecting the images, by using a plurality of preliminarily input three-dimensional images of the artificial joint; means for installing an alignment rod which, based on the artificial joint installed by the means for installing the femur side artificial joint, reference points of the knee joint, and preliminarily input three-dimensional images of an alignment rod in marrow inserted into the femur by the artificial knee joint replacement operation, accepts input of an installation position of the alignment rod in the marrow; means for determining a first parameter which determines various parameters that can be directly measured from the knee joint including an adjustment value of a first jig to specify an insertion position, insertion orientation and insertion depth of the alignment rod in the marrow, based on the position of the alignment rod in the marrow installed by the means for installing the alignment rod relative to the three-dimensional images of the femur; and means for determining a second parameter which determines various parameters that can be directly measured from the knee joint including an adjustment value of a second jig to specify a position of a bone cutting surface at a jig for bone cutting mounted at the alignment rod in the marrow to cut bone and a rotation angle of the bone cutting surface, based on the installation position of the artificial joint installed by the means for installing the femur side artificial joint relative to the three dimensional images of the femur and the position of the alignment rod in the marrow installed by the means for installing the alignment rod relative to the three-dimensional images of the femur.