provided are turbine blades and a gas turbine capable of damping the vibrations caused by an excitation force and facilitating mounting / disassembly . included are a shroud portion disposed at an end portion of an airfoil portion ; a holder casing that can slide relative to the shroud portion , that can also be attached thereto / detached therefrom , and that forms a space with the shroud portion therebetween ; and an elastic portion that is disposed in the space , that biases the shroud portion in a direction that separates it from the holder casing , and is disposed in a movable manner relative to the shroud portion ; and a pressing portion that is disposed between the elastic portion and the holder casing and that can be moved toward and away from the shroud portion .