This　paper　examines　the　nonlinear　seismic　responses　of　New　Saikai　Bridge,　which　has　a　main　span　length　of　230　m　and　is　the　first　CFT　arch　bridge　of　highway　bridges　in　Japan.　Using　a　three-dimensional　FE　model,　in　which　the　fiber　model　is　used　to　consider　the　material　nonlinearity　and　the　P-8　effect　are　used　to　consider　the　geo-metric　nonlinearity.　The　nonlinear　seismic　characteristics　and　seismic　performance　of　this　bridge　are　examined　in　detail　by　subjecting　the　bridge　to　strong　earthquakes　in　the　out-of-plane　direction,　the　longitudinal　direction,　or　the　combined　out-of-plane　and　longitudinal　directions.　It　is　shown　that:　the　axial　forces　are　predominant　when　subjected　to　an　earthquake　in　the　out-of-plane　direction;　the　axial　forces　and　out-of-plane　bending　moments　are　predominant　when　subjected　to　an　earthquake　in　the　longitudinal　direction;　the　responses　subjected　to　earthquake　in　the　out-of-plane　direction　are　larger　than　those　in　the　longitudinal　direction　;　the　effect　of　the　combined　out-of-plane　and　longitudinal　excitations　should　be　considered.