In this thesis, two-dimensional floating structure consists of single rectangular impermeable pontoon and single cable is studied.The purpose of this study is to obtain the motion analysis of incident waves acting on a floating with cable-restrained. All boundary conditions are linearlized in the problem which is separated into a scattering problem and radiation problem with unit motion amplitude. The method of separation of variable is used to solve for velocity potentials. Divide two kinds of discussions in cable-restrained¡G1¡BWith sag effective and flexural rigidity. 2¡BNO sag effective and no flexural rigidity. The boundary value problem with nonhomogeneous boundary condition beneath the structure is solved by using a solution procedure proposed by Lee(1995). By combining the scattering solution, radiation solutions of three degrees of freedom, and equations of motion of the floating structure, an analytic solution for the problem is developed.