Nam Nao (Thai: น้ำหนาว, pronounced [náːm nǎːw]) is the northeasternmost district (amphoe) of Phetchabun province, northern Thailand.

On 16 November 1978 the tambons Nam Nao and Lak Dan were split from Lom Sak district and made into a minor district (king amphoe).

The district's east side borders Phu Kradueng Mountain.

Nam Nao National Park is in the district.

The district is divided into four sub-districts (tambons), which are further subdivided into 30 villages (mubans).