Floating breakwaters (FBs) have been widely used as an alternative solution to protect coastal sites especially small harbors and certain areas which are not suitable for rubble mound breakwaters. Floating breakwater cannot completely stop the incident wave action. Instead, it attenuates the wave action by partially transmitting, partially reflecting, and partially dissipating the incident wave. The efficiency of the FBs profiles and configurations can be quantified by its transmission coefficient which is the ratio of the significant wave height at the lee side of the FBs over the significant wave height at the front side. The aim of this master thesis was to perform a numerical analysis of FBs structures by means of WAMIT and MultiSurf. The study was focused on the wave transmission behind the FBs and the response motions of the structure. Twelve cases based on laboratory experiments were numerically analyzed and some of the results were compared to available measurement data. Some results were satisfactorily confirmed to the experiment result while other results were still far from perfect. Some improvement methods were recommended to be carried out in the future work i.e. trying out more structure geometry representation, simulating more cases which are comparable to the experiments, and more detail study of how the experiments were carried out and how the final outputs were calculated.