The vibration characteristics of truss type quay wallwithinclined steel piles is studied by model vibration tests and dynamicanalyses. The structural merits of the quay wall discussed here are
　(a)decrease of the earth pressure by an inclined wall and
　(b) strong resistance in the axial direction of the inclined piles against seismic load. The following results obtained by this study:
(1)The dynamic response of truss type quay wall is dominant near by resonant frequency of ground and structure.
(2)The dynamic external force is supported in the axial direction of the inclined piles. But ground vibration sometimes took place bending strain in piles.
(3)The quantitative resutls obtained by the FEM analysis using equivalent linear method well agree with that of the experiment.
(4)It is necessary for seismic design of truss type quay wall to consider the dynamic characteristics of ground and structure.