PURPOSE: To solve constraint of a space in the arranging position of an elastic plasticity damper, miniaturize a scale, and simultaneously exhibit stable energy absorbing performance.

CONSTITUTION: An elastic plasticity damper 1 is made of a steel member formed in a hollow cross section shape, arranged between structure members 2 separated being allowed relative rotating deformation each other around an axis, being brought contact with each structure member 2 in condition in which twist moment is loaded at the time of relative rotating deformation caused between both structure members 2, and provided for absorbing energy by yielding twist. Since yielding is carried out by twist moment, constraint of a space in the arranging position is solved, a scale is miniaturized, and simultaneously stable energy absorbing performance is exhibited.