The Leuweung Sancang Nature Reserve has ecosystem diversity, including seagrass beds, with a variaety of natural resources that are important to be preserved. Apart from being a food source for herbivorous organisms, seagrass beds also function as shelter and breed for many marine invertebrates, including Echinoderms. Association between Echinoderms and seagrass was observed in this study to investigate the interaction. Sampling was carried out in 1x1 m 2 plots which were placed in 3 transect lines of 250 m long, with a plot intervals of 25 m on each transect line. The transect line extended from the beach heading to the shore, and was carried out in 4 different stations, namely Ciporeang, Cipunaga, Cikolomberan, and Cipangikisan. Observation had been done to determine diversity, density, coverage, and evenness of both seagrass and Echinoderms, thus to study the correlation between them. The results showed that there were 2 seagrass species, Thalassia hempricii and Cymodocea rotundata, and there were 2 families of Echinoderms: Ophiocomidae and Holothuridae. Result of Rank-Spearman correlation coefficient showed possitive association between seagrass and echinoderms in all stations being observed, but only in Cikolomberan that showed significantly high association.