It is necessary to estimate the amount of air-borne sea salt adhered to each member of a structure accurately for more efficient maintenance and management. In this study, the concentration of air-borne sea salt and the mechanism of the adhesion to a structural surface are discussed. First, air-borne sea salt is collected in the field using the originally developed device and the concentration is calculated. Next, the flow field around a structure is simulated. Then the amount of the adhesion is estimated, considering inertial collision and diffusive motion of sea salt particles and washing-out effect by precipitation. Finally, the predicted distribution of the amount of sea salt on the surface is compared to those by field observation.