This paper addresses optimal motion control for nonholonomic systems with a passive joint. We propose a motion-planning method that combines a rapid semi-optimal motion-planning method (RASMO) and an output-zeroing method. First, a semi-optimal motion is calculated using RASMO, following which the motion is converted to a flow in a phase space using the output-zeroing method. To validate the proposed method, we conducted a throwing experiment using a two-link arm. As a result of the experiment, planned semi-optimal motion was realized precisely in the nonholo-nomic system. Using this approach, we have enhanced the applicability of RASMO to nonholonomic systems with a passive joint.