The　earthquake　input　is　required　when　the　soil-structure　interaction　(SSI)　analysis　is　performed　by　the　direct　finite　element　method.　In　this　paper,　the　earthquake　is　considered　as　the　obliquely　incident　plane　body　wave　arising　from　the　truncated　linearly　elastic　layered　half　space.　An　earthquake　input　method　is　developed　for　the　time-domain　three-dimensional　SSI　analysis.　It　consists　of　a　new　site　response　analysis　method　for　free　field　and　the　viscous-spring　artificial　boundary　condition　for　scattered　field.　The　proposed　earthquake　input　method　can　be　implemented　in　the　process　of　building　finite　element　model　of　commercial　software.　It　can　result　in　the　highly　accurate　solution　by　using　a　relatively　small　SSI　model.　The　initial　condition　is　considered　for　the　nonlinear　SSI　analysis.　The　Daikai　subway　station　is　analyzed　as　an　example.　The　effectiveness　of　the　proposed　earthquake　input　method　is　verified.　The　effect　of　the　obliquely　incident　earthquake　is　studied.