Titanium (Ti) is widely used for oral cavity biomedical devices. However, because it penetrates the mucosa and exists partially external to the tissue, it sometimes induces tissue inflammation, minor infection, or peri-implantitis due to oral bacteria after implantation and causes serious consequences. We have previously shown that poly(ethylene glycol) (PEG)- electrodeposited Ti inhibits bacterial adhesion and biofilm formation. However, the effect of the PEG coating in body fluid is still unclear. In this study, we investigated bacterial colony morphology and biofilm formation on PEG-electrodeposited Ti in comparison with untreated Ti in the presence of saliva. After 48 h incubation, Streptococcus mutans biofilms adhered on the untreated Ti were rigid and cohesive, while those on the PEG-electrodeposited were loose and were easily washed off. These results indicate electrodeposited-PEG layers inhibit the biofilm formation on Ti in the presence of saliva.