A computer is caused to execute an image inputting step (S101) of inputting a plurality of two-dimensional tomographic images of the lower limbs including the pelvis and the femur, an image reconstructing step (S102, S103) of reconstructing a threedimensional image including the pelvis and the femur from the plurality of two-dimensional tomographic images, an artificial joint determining step (S104, S105) of determining an artificial joint which is to be set to the acetabular cartridge of the pelvis, a setting position, and a setting direction from the three-dimensional image of the pelvis and the femur, a base jig setting step (S107-S109) of setting a three-dimensional image of a base jig having three support columns which are in contact with three landmarks of the pelvis with respect to the three-dimensional image of the pelvis, and a parameter obtaining step (S110-S112) of parameterizing and obtaining a direction of a line which passes through the upper end of a support column in immediate proximity to the acetabular cartridge of the pelvis in the three-dimensional image of the base jig and is parallel to the setting direction of the artificial joint.
