Bang Saphan (Thai: บางสะพาน, pronounced [bāːŋ sā.pʰāːn]) is a district (amphoe) in the southern part of Prachuap Khiri Khan province, central Thailand.

King Nangklao (Rama III) of Rattanakosin established Kamnoed Nopphakhun as a fourth-class city under the Kalahom (defence ministry).

King Chulalongkorn (Rama V) downgraded the city to Mueang Kamnoed Nopphakhun District.

In 1915 King Vajiravudh (Rama VI) renamed the district by removing the word Mueang off.

To the west are the Tenasserim Hills and the Tanintharyi Division of Myanmar, to the east the Gulf of Thailand.