Sam Ngao (Thai: สามเงา, pronounced [sǎːm ŋāw]) with Tha Song Yang district is the northernmost district (amphoe) of Tak province, western Thailand.

Originally named Tha Pui (ท่าปุย), it was renamed "Sam Ngao" in 1939.

The important water resources of the district are the Ping and Wang Rivers.

The Bhumibol Dam is an artificial lake of the Ping River for flood control and for generating electricity.

The district is divided into six sub-districts (tambons), which are further subdivided into 43 villages (mubans).