Sanmon is assumed to represent Sangedatsumon (Three Gates of Liberation), which consists of three gates symbolizing three mental states, that is, kumon (gate symbolizing emptiness), musomon (gate symbolizing formlessness) and muganmon (gate symbolizing desirelessness), to pass through before reaching the Buddhist paradise.
三門は空門・無相門・無願門の三境地を経て仏国土に至る門、三解脱門（さんげだつもん）を表すとされる。