Present states of resources, strength, durability of timber structures were reviewed.Then trial designs of wharves with timber structures were carried out. Design depths (5-10m), seismic factors (0.02-0.27) and surcharges (5-20kN/m2) were varied as parameters. The structural type of the wharves was a marginal wharf supported on vertical piles. The structural members of the wharves were steel pipe piles and reinforced concrete (RC) superstructures for the series of basic cases, steel pipe piles and EWP superstructures for another series of cases, and EWP (glued laminated timbers or logs) piles and EWP superstructures for the other series of cases.
　As the results of the trial designs, 1.Weight of superstructures significantly decreased by using EWP superstructures instead of RC superstructures. Required amounts of steel pipe piles could be saved up to 50% due to the light weight of EWP superstructures when seismic forces were the dominant design lateral forces. 2.The minimum value of the ratio of the volume of timber piles(m3) to the weight of steel pipe piles(t) was about 1.6 as the result of the trial designs using timber piles instead of steel pipe piles. It is possible that using timber piles would be economical if the ratio of the price of timber to that of steel in Japan were as that in most foreign countries.