A database for calculating a physiologically appropriate muscle tension by using only motion data invasively determined is constructed. Disclosed is a method for constructing a muscle tension database using motion data acquired for each frame when a subject expressed by a muscle skeleton model makes a predetermined motion and the tensions of the muscles of the muscle skeleton model. The motion data is specified by joint angle data about each joint of the muscle skeleton model for each frame. A muscle group of muscles in antagonistic/cooperative relation driving each joint of the muscle skeleton model is defined for each joint. The muscle tension ratio of each muscle of each muscle group is determined by using the muscle tensions. Muscle tension ratio data is created for each frame. The joint angle data is associated with the muscle tension ratio data for each frame. The joint angle data and the muscle tension ratio data associated with the joint angle data are stored. Thus, a muscle tension database about the predetermined motion is constructed.
