Pak Thong Chai (Thai: ปักธงชัย, pronounced [pàk tʰōŋ t͡ɕʰāj]) is a district (amphoe) in the southern part of Nakhon Ratchasima province, northeastern Thailand.

King Taksin the Great changed the name of the city to Pak Thong Chai and set aside this area for Lao people from Vientiane kingdom.

He promoted Phia Upparacha of Vientiane to be Phraya Wongsa Akkharat (พระยาวงษาอรรคราช), the governor of Pak Thong Chai.

King Chulalongkorn (Rama V) changed the city status to a district (amphoe) in 1908 as part of the thesaphiban administrative reforms.

Neighboring districts are (from the north clockwise): Sung Noen, Mueang Nakhon Ratchasima, Chok Chai, Khon Buri, and Wang Nam Khiao.