The titania containing TiO2 as a major component was prepared simply by irradiating carbon dioxide laser on the surface of a titanium plate, and the growth on its surface of Eschelichia coli, Bacillus subtilis or Saccharomyces cerevisiae was inhibited depending on energy densities of irradiated laser. Furthermore, the titania also showed antimicrobial activities against marine microbes after soaking the preparation into the sea water for several days. These results suggested that the antimicrobial titania would prevent the adhesion of marine fouling organisms on undersea-structures by the inhibition of the bacteriofilm formation, which is an early step of marine bio-adhention.