Macrobenthic fauna were studied on a tidal flat in Garolim Bay in July 2002, in order to understand their spatial distribution with the surface sediment types. Forty-nine stations were set on the tidal flat. A total of 147 species was sampled with the mean density of 1,140ind./m2 and the mean biomass of 157.2g/m2. The polychaetes were speices- and density-dominant faunal group with 64 species and the mean density of 791ind./m2. Mollusks were biomass-dominant faunal group with 132.0g/m2. Major dominant species were two polychaetes, Mediomastus californiensis with the mean density of 347ind./m2 and Heteromastus filiformis with 224ind./m2. Also mollusks such as Umbonium thomasi, Batillaria cumingi and Ruditapes philippinarum was relatively high in the mean density, showing the density of 45, 42, 32ind./m2 respectively. Especially, U. thomas was distributed in the mouth of the bay, where sediment grain size is rather coarse, and R. philippinarum at near tidal channel. Based on the cluster analysis, the macrobenthic community on the tidal flat was classified into seven station groups depending on the benthic environmental parameters(sediment types). Compared with other Korean tidal flats, species richness of Garolim tidal flats is more and less low.