Government policy aims at increasing the use of wood for public buildings recently in Japan. In case of the use of wood for port facilities, the main deterioration factors are marine borers such as teredo and limnoria for submerged members and weathering for non-submerged members. In this study, the difference of marine borers' attacks among wood species, the effect of the attacks on the strength of wood materials, the usefulness of some protective methods against marine borers and the attacks on the wood in sand were investigated by submergence tests in the seawater, and the difference of weathering properties among wood species was examined by exposure tests in coastal atmosphere.
　The following results were obtained: (1)The submergence tests of 15 species of wood showed that Kusunoki (Cinnamomum camphora) and Kaya (Torreya nucifera) suffered smaller damages rather than other species. A correlation was found between the limnoria's attacks and the hardnesses or the specific gravities of wood materials. (2)The relationship between the weight losses and the strength reductions was common for all the species, shapes, sizes and durations of submergence, and the percentages of the strength reductions were larger than those of the weight losses. (3)The protective methods such as covering with polyethylene meshes (PE100 and PE150), heat treatment (237.5 degrees Celsius, 5 hours) and low-molecular phenol resin injection treatment could significantly reduce damages. (4)As the results of two-year submergence of wood blocks buried in sand, there was no marine borers' attachment on the wood surfaces covered by sand. (5)The results of the exposure tests in a coastal atmosphere with additional seawater spray showed that the weights, sizes and bending stiffnesses of hardwood decreased more rapidly than those of softwood.