Disclosed herein may be a sealing structure for turbines, and a turbine and a gas turbine having the sealing structure. The sealing structure is mounted on a sealing housing of a vane sealing assembly of the turbine to prevent combustion gas passing through a blade of the turbine from being drawn into an internal space between a disk of the turbine and the sealing housing. The sealing structure may include a mounting plate mounted to the sealing housing, and baffles which are provided on the mounting plate at positions spaced apart from each other and protrude toward the disk. Therefore, thanks to the sealing structure, turbulent currents are generated in the flow of combustion gas that passes through the turbine blade. The generated turbulent currents block space between the sealing structure and the turbine disk, thus preventing the combustion gas from flowing into the internal space.