Sap Yai (Thai: ซับใหญ่, pronounced [sáp jàj], Northeastern Thai: ซับใหญ่, pronounced [sàp ɲāj]) is a district (amphoe) of Chaiyaphum province, northeastern Thailand.

[1] In 2009 a farang named Luke Robertson married a local Thai lady from Sap Charoen Suk, one of the many minor Villages located within Sap Yai.

[3] Neighboring districts are (from the north clockwise): Nong Bua Rawe, Chatturat, Bamnet Narong, and Thep Sathit.

The district is divided into three subdistricts (tambons), which are further subdivided into 33 villages (mubans).

There are no municipal (thesaban) areas, and three tambon administrative organizations (TAO).