Abstract: An apparatus for measuring stress of viscoelastic material in which a rotational die and a torque detecting die are provided, an outer cylindrical die is provided around the torque detecting die, the diameter of the rotational die is arranged to be larger than the diameter of the outer cylindrical die, and the surface forming one part of a sample chamber has such configuration that a slipping of the sample contained in the sample chamber is prevented, so that a shearing speed having no disorder can be given to the sample mounted all over a surface, forming the sample chamber, of the torque detecting die.