Kantharalak (Thai: กันทรลักษ์, pronounced [kān.tʰā.rā.lák]) is a district (amphoe) in the southeastern part of Sisaket province, northeastern Thailand.

[1] The name Kantharalak means 'countless ravines', from Pali kandara ('ravine') and the Sanskrit lakṣa (लक्ष), 'a hundred thousand'.

Neighboring districts are (from the west clockwise): Khun Han, Si Rattana, and Benchalak of Sisaket Province; Thung Si Udom and Nam Khun of Ubon Ratchathani province; Preah Vihear and Oddar Meancheay of Cambodia.

The district is divided into 20 subdistricts (tambons), which are further subdivided into 279 administrative villages (mubans).

Missing numbers belong to tambon which now form Benchalak district.