Provided are an internal olefin sulfonate composition which is capable of sufficiently enhancing foamability, foam spreadability, and foam dissipation property, and a cleansing composition containing the same. The internal olefin sulfonate composition comprises (A) an internal olefin sulfonate having 16 carbon atoms and (B) an internal olefin sulfonate having 14 carbon atoms, wherein a content mass ratio of the component (A) to the component (B), (A/B), is from 10/90 to 70/30, and a content of the internal olefin sulfonate having 18 or more carbon atoms is 5% by mass or less.