PURPOSE: To obtain proper wave dissipation effect by a method wherein a plurality of rotatable plates arranged in parallel at proper intervals are provided in a floating manner on the sea through the intermediary of floating bodies and thereby the energy of waves is absorbed effectively.

CONSTITUTION: Plate-supporting bars 2 in plural are laid in parallel between floating bodies 1 set at a certain interval and both ends of each bar 2 are fixed to the floating bodies 1. On the other hand, from these plate-supporting bars 2 are suspended curtainlike plates 3 in such a manner that the plates 3 can rotate around the bars 2 as the supporting points by the force of waves.