This study investigates the composition and abundance of tidal pool fish in Seongsan of the Jeju Island, Korea. The fishes were sampled every month from January to December 2017. A total of 463 specimens were sampled, which belonged to 51 species in 23 families including two unidentified species. Labridae (6 species), Gobiidae (6 species), and Blenniidae (5 species) species were predominant taxon. Dictyosoma rubrimaculatum and Enneapterygius etheostomus were most present during 9 months in the year. In terms of period, abundance was the highest in August and September as 20 species, and lowest in the February as 4 species. On the other hand, diversity index was the highest in June (H’=1.155), and lowest in February (H’=0.538). Total biomass was the highest in May (179.11g), and lowest in February (8.51g). In cluster analysis, two differentiated seasonal group was confirmed (from December to March and April to November), but August and October show unusual aspect in comparison to other seasonal compositions. Compared to the previous study, fifty-one species in this study is lower than previous reported, but seventeen species represent new records for the Seongsan. Therefore, it seems that tidal pool on Seongsan is used for habitats of many more fishes.