Cl^–-pump rhodopsin is the second discovered microbial rhodopsin and functions as light-driven Cl^– pump. The physiological significance of the Cl^– pump has not been fully resolved. However, its functional mechanism has been studied as a model system of anion transporters. In this review, the variation and functional mechanisms of Cl^–-pump rhodopsins were summarized. After 2014, novel Cl^–-pump groups were discovered in marine and terrestrial bacteria and were revealed to have unique characteristics. The most recently identified protein has close similarity with the H⁺-pump rhodopsin and begins to pump H⁺ outwardly by only a single amino acid replacement.