The gate came to be called by its nickname Hamaguri-Gomon Gate because it was the gate that rarely opened, but it opened like a hamaguri (clam) when the imperial palace burned in the Great Kyoto Fire of the Tenmei period during the reign of Emperor Kokaku.
光格天皇の時に発生した天明の京都大火において御所が炎上した折に、滅多に開かなかったこの門がこの時だけは開いたというので蛤のような門、転じて蛤御門という俗称が付いた。