Post-failure　field　investigation,　instrumentation,　monitoring,　and　numerical　simulation　were　performed　to　give　insights　into　the　failure　mechanism　of　a　13-h-delayed　rainfall-induced　landslide.　A　conceptual　hydrological　model　was　postulated　based　on　the　findings　obtained　from　the　investigation　works.　The　results　showed　that　subsurface　flow　was　recharged　by　intense　and　prolonged　rainfall　through　outcrops　of　fissured　bedrock.　The　recharged　water　was　mounded　in　the　moderately　weathered　granite　layer　and　caused　an　increase　in　hydraulic　head.　The　groundwater　seeped　gradually　upward　into　the　overlying　fill　layer　even　after　the　rain　has　ceased,　and　eventually　triggered　the　landslide　when　the　water　table　was　raised　to　a　critical　state.　As　most　of　the　existing　hydrologic-slope　stability　models　were　developed　on　the　basis　of　soil-impermeable　bedrock　model,　this　could　result　in　great　discrepancies　between　the　simulated　results　and　the　real　hydrological　responses　of　the　slope.　The　findings　from　the　present　study　highlighted　the　importance　of　considering　subsurface　flow　and　hydro-geological　features　in　assessing　the　mechanism　of　rainfall-induced　landslide.