Efforts to preserve mangrove forests through species diversity inventory are important input data in mangrove forest management. The purpose of this research is to investigate the potential and diversity of mangrove forest species in Ruar village, Biak Numfor Regency, Papua Province. Inventory of mangrove species using the grid line method which is laid systematically. The distance between the lanes is determined to be 200 meters and plots are placed to the left and right of the lanes, making up as many as six lanes/transects. The results of this study, there are 5 species, namely Sonneratia alba, Rhyzophora stylosa, Rhyzophora apiculata Bl, Bruguiera gymnorhyza (L) Lamk, Ceriops tagal (Perr). C.B.Rob. On tree growth rates were dominated by Rhyzophora apiculate Bl (INP 152.73%), sapling and seedling rates dominated by Bruguiera gymnoriza (L) Lamk (INP 137.85% and INP 128.46%). Species diversity index according to tree growth rate (0.874), sapling rate (0.678) and seedling rate (0.667). According to Shannon-Wienner criterion (H’ <1), the species diversity index in the mangrove forest of Ruar Village, Biak Numfor Regency is low. Species enrichment planting activities are needed in maintaining and increasing the diversity of mangrove species to control environmental disturbances.