A damper comprising: a vessel; a partitioning member which partitions an interior of said vessel into two accommodation chambers (4, 5) for accommodating a viscous fluid, and which rotates together with said vessel about an axis of said vessel and is movable in an axial direction of said vessel; moving force imparting means for imparting to said partitioning member a moving force in one axial direction by the input of relative rotation about the axis of said vessel with respect to said vessel, so that a moving velocity is set to one corresponding to a rotating velocity of the input of rotation; resilient means for resiliently urging said partitioning member in another axial direction; a through hole formed in said partitioning member so as to allow the two accommodation chambers (4, 5) inside said vessel to communicate with each other; and being characterised in that it further comprises an allowing/limiting member which is resiliently urged in the one axial direction to allow the viscous fluid accommodated in said two accommodation chambers (4, 5) in said vessel to flow reciprocally between said two accommodation chambers (4, 5) through said through hole, and which limits the flow of the viscous fluid in said accommodation chamber in the one axial direction into said accommodation chamber in the other axial direction through said through hole against the resilient urge in the one axial direction allowing that flow, when the internal pressure of the viscous fluid accommodated in said accommodation chamber in the one axial direction is generated in excess of a fixed value on the basis of the movement of said partitioning member in the one axial direction. a vessel; a partitioning member which partitions an interior of said vessel into two accommodation chambers (4, 5) for accommodating a viscous fluid, and which rotates together with said vessel about an axis of said vessel and is movable in an axial direction of said vessel; moving force imparting means for imparting to said partitioning member a moving force in one axial direction by the input of relative rotation about the axis of said vessel with respect to said vessel, so that a moving velocity is set to one corresponding to a rotating velocity of the input of rotation; resilient means for resiliently urging said partitioning member in another axial direction; a through hole formed in said partitioning member so as to allow the two accommodation chambers (4, 5) inside said vessel to communicate with each other; and being characterised in that it further comprises an allowing/limiting member which is resiliently urged in the one axial direction to allow the viscous fluid accommodated in said two accommodation chambers (4, 5) in said vessel to flow reciprocally between said two accommodation chambers (4, 5) through said through hole, and which limits the flow of the viscous fluid in said accommodation chamber in the one axial direction into said accommodation chamber in the other axial direction through said through hole against the resilient urge in the one axial direction allowing that flow, when the internal pressure of the viscous fluid accommodated in said accommodation chamber in the one axial direction is generated in excess of a fixed value on the basis of the movement of said partitioning member in the one axial direction.