Ban Na San (Thai: บ้านนาสาร, pronounced [bâːn nāː sǎːn]) is a district (amphoe) of Surat Thani province, Thailand.

The eastern portion of the district is within the Nakhon Si Thammarat mountain range and is part of Tai Rom Yen National Park.

Originally the district was divided into seven tambons: Ban Na, Tha Ruea, Kobkaeb, Thung Tao, I-Pan, Prasaeng, and Phanom.

Originally the district was administered from Nakhon Si Thammarat, and was transferred to Chaiya (now Surat Thani) in 1906.

Thailand's first rambutan trees were planted in Ban Na San in 1926 by the Chinese Malay K. Vong.