Biofilm is a starting point of biofouling and biocorrosion. However there was not enough informations about the biofilm forming bacteria in marine environments. In the present study, phylogenetic position and bacterial properties thought to be concerned in biofilm formation such as cell surface hydrophobicity, attachment on surface, production of quorum sensing (QS) signal molecule etc. were investigated for 76 isolates of 3 days old biofilm. Based on the partial sequences of 16S rDNA, the isolates could be assigned to 30 known genera which have been reported as widespread in marine environment. Approximately 31% of the isolates had been reported previously as uncultured or unidentified in GenBank database. Cell surface hydrophobicity and attachment ability were usually incompatible in a same strain except two strains. Among the 39 strains producing Acyl-Homoserine Lactone (AHL), 21 strains could degrade AHL molecules. Among the isolates, high values of cell surface hydrophobicity were found in the strains belong to high GC gram positive group and attachment ability was relatively high in low GC gram positive bacteria. To the contrary, average value of EPS productivity was highest in γ-Proteobacteria. These results implied that the role of bacterial strains in the process of biofilm formation is closely related to the phylogenetic position.