In natural and industrial environments, bacteria exist in adhering to solid surfaces such as metals, plastics, glass, soil particles, plant and animal tissues. Adherent bacteria are resistant to chemicals and heat compared with their planktonic cells, and may cause serious problems in bioprocess engineering, medicine and food processings. In order to clarify these observations and phenomena, it is necessary to study physicochemically the microstructure of solid surfaces, structure and properties of bacterial cell surfaces, mechanisms of bacterial adhesion and their correlations.