To improve collecting efficiency by circulating a plurality of containers arranged between right and left single body ship of a catamaran ship with the suitable distance, continuously collecting wastes floating on the water surface to the containers, and making the containers float on the water surface during sailing of the ship.

When wastes floating on the water surface are collected, an endless chain 4 is made to circulate by sprockets 3, and a single container 7a is half immersed in water and stopped in the suitable position. The wastes are collected while a collecting ship is slowly sailed. When the container 7a is filled with the wastes, the containers 7a to 7d are circulated, the container 7a is lifted from the water surface, and the next container 7b waiting by now is half immersed and made to be ready to collect the wastes, and the wastes are collected. In cruising, the single container 7a is detached from the endless chain 4 and transferred to a container putting place 30, so as to be prevented from immersed in the water.