Various facilities such as offshore wind farms have been constructed at sea in recent years. In general, offshore facilities cannot avoid damage caused by waves. This may result in accidents, such as vessels drifting and capsizing as well as collision with marine structures. If wave-free space can be created on the free surface of the sea, we can reduce such wave accidents. Additionally, it leads to further development in offshore utilization such as floating cities. In this study, we aim to create a wave-free space within an annular floating structure consisting of multi-layered elastic plates. We establish the numerical simulation method to solve the wave field around this plate based on the eigenfunction matching method. In addition, we derive the inside wave energy in the annular plate. To achieve wave-free space within the plate, the evolutionary optimization method, Covariance Matrix Adaptation Evolution Strategy (CMA-ES), is employed for seeking the optimum plate design. We designate two parameters associated with each layer of the thin plate as design variables and optimize them to minimize the wave energy inside the circular structure. Optimization is carried out at the specific wave number. We compare the wave displacement around the circular float structure in two cases: (1) when only the wave energy inside the structure is minimized and (2) when both the inside wave energy and the outside scattered wave energy are minimized. Since the plate is the annular ring, the wave-free performance is omnidirectional.