When the hook of a crane-barge carries loads under wave condition, it is important to estimate motion of the ship, the hook, and the shackle for work safety. The hook and the shackle motions are mutually combined motions between the crane-barge, the hook and shackle swing. In this study, analytical model for coupled motion between crane-barge, hook, and shackle was proposed and verified experimentally; by a crane-barge model and by double pendulum model. In addition, analytical study for the development of reduction of the hook and the shackle swing motion method was conducted. By this analytical model, we proposed a way of reducing the hook and the shackle swing on a crane-barge under wave condition.