To develope seaweed transplantation method to reduce grazing pressure by Anthocidaris crassispina, seaweed biomass and number of sea urchin were examined after 2 days from Ecklonia cava transplantation by four ways (three floating rope methods and seaweed transplantation block method). Three floating rope methods were different in the seaweed rope connection to fixation block rope; direct connection, polypropylene rope connection, and stainless wire connection. About twenty sea urchins were found on the seaweed cultivation rope connected directly to fixation block rope and on transplantation block. However no sea urchin was found for 2 days on the seaweed cultivation ropes connected by stainless wire and polypropylene rope. After 2 days from seaweed transplantation, biomass of E. cava was maximal with 992.61 ± 78 g m-1 in wet weight on stainless wire connection method and minimal in seaweed transplantation block method with 121.85 ± 71.67 g m-1. Before transplanting 42 Ecklonia cava plants were on one meter of cultivation rope and 41 plants on the cultivation rope connected with stainless wire to fixation block but five plants were remained on the transplantation block after 2 days. In conclusion, the best transplantation method of E. cava in this study to reduce grazing pressure of sea urchin was a floating rope method connected stainless wire to fixation block.