An applicator of a cosmetic product, typically designed to cooperate with a neck of a holder containing said cosmetic product, for example mascara, comprises a head forming a means of manually gripping said applicator, an axial stem and an application means, and is characterized in that it comprises a means of rotation of said axial stem, said means of rotation comprising a fixed part attached to said head, and a rotating part attached in rotation to said axial stem, and a manual means of activation and/or deactivation of said means of rotation, so as to form a rotary applicator, said axial stem and said application means attached to said axial stem being able to be rotated especially when a user of said applicator applies said cosmetic product, typically to the eyelashes, by manually gripping said head.