From a desired wrist joint position and a desired elbow rotation angle, a temporary elbow joint position is calculated on the assumption that a distance between a shoulder joint and an elbow joint is fixed. The shoulder joint has a first axis, a second axis, and a third axis, and the elbow joint has a fourth axis. From the calculated temporary elbow joint position, temporary angles of the first and second axes or temporary angles of the first to fourth axes are determined. The temporary angles are corrected in accordance with at least one evaluation function calculated from the temporary angles.