The invention discloses a supporting device used in the process of polishing toenail plates or coating the surfaces of the toenail plates with a fluid, and belongs to the technical field of toenail polishing tools. The supporting device comprises a cylindrical support body, wherein the support body is rotatably mounted on a bracket; the support body is composed of a toe supporting part and a rotating cylinder; the toe supporting part is located at the upper half part of the support body; five toe separating grooves, which correspond to toes of a person and have two transparent ends, are uniformly formed in the upper part of the toe supporting part; extending directions of the toe separating grooves are perpendicular to an axial direction of the support body; two inner sides of each of the toe separating grooves are made of elastic materials; spacing parts between the toe separating grooves form toe separating blocks; the rotating cylinder is fixedly connected to a position under the toe supporting part and is butt-jointed with the toe supporting part to form a complete cylinder; a rotating shaft is fixedly connected with the two ends of the rotating cylinder and mounted on the bracket through a bearing. The supporting device has the rotary support body, thereby being capable of easily adjusting angles and positions of the toes and greatly improving the operation convenience and foot comfort.