In recent years, the oceans debris is increased because of human’s activity. Especially, the plastic debris, such as plastic bottles, is not biodegradable, and therefore those are creating serious environmental problems. The ocean debris collecting in the world is done through volunteer activities. However, these activities require a lot of time and labor. In this research, we proposed a method of ocean debris collecting USV operation method. Also, we designed and developed a USV (Unmanned Surface Vehicle) for the purpose of autonomous oceans debris collecting mission and evaluated the developed ocean debris collecting device. In the development of USV, electronic parts, which are to operate the mission autonomously, were selected. Then, each electronic part was placed inside the waterproof box according to the designed power and communication system diagram. In the development of oceans debris collecting device, we designed a belt conveyor type device. A motor was selected to rotate the device and a decelerator, which used the planetary gear mechanism, was designed. To evaluate the performance of the developed ocean debris collecting device, we tested various types of plastic bottles in tank environment. As a result of the experiment, the developed USV collected various types of plastic bottles with a 47.7% probability.