A damper generating a damping force in reaction to an external force by limiting a movement of a viscous fluid, the damper comprising: a fluid holding chamber having an opening portion and holding the viscous fluid; a resistance generating member inserted into the fluid holding chamber, the resistance generating member being movable relative to the fluid holding chamber by the external force; a volume changing means partitioning an inside of the fluid holding chamber, and the volume changing means compressing one of areas and expanding another of the areas in the partitioned fluid holding chamber with a movement of the resistance generating member relative to the fluid holding chamber; a flow path (36; 936) connecting between the areas in the fluid holding chamber partitioned by the volume changing means; and an elastic member of annular shape (8a, 8b), arranged between the resistance generating member and the fluid holding chamber; the elastic member (8a, 8b) comprising: an inner peripheral surface having a width in a direction of a center axis of the fluid holding chamber and being pressed against the resistance generating member; and an outer peripheral surface having a width in the direction of the center axis of the fluid holding chamber and being pressed against the fluid holding chamber, wherein the width, in the direction of the center axis of the fluid holding chamber, of the inner peripheral surface of the elastic member (8a, 8b) is smaller than the width, in the direction of the center axis of the fluid holding chamber, of the outer peripheral surface of the elastic member (8a, 8b), characterised in that the elastic member (8a, 8b) comprises: an inner periphery side annular portion having a rectangular cross section and including the inner peripheral surface of the elastic member (8a, 8b); an outer periphery side annular portion having a rectangular cross section and including the outer peripheral surface of the elastic member (8a, 8b); and a coupling portion connecting between the inner periphery side annular portion and the outer periphery side annular portion, the coupling portion having a width smaller than the widths (t6, t7) of the inner periphery side annular portion and the outer periphery side annular portion, in the direction of the center axis of the fluid holding chamber. a fluid holding chamber having an opening portion and holding the viscous fluid; a resistance generating member inserted into the fluid holding chamber, the resistance generating member being movable relative to the fluid holding chamber by the external force; a volume changing means partitioning an inside of the fluid holding chamber, and the volume changing means compressing one of areas and expanding another of the areas in the partitioned fluid holding chamber with a movement of the resistance generating member relative to the fluid holding chamber; a flow path (36; 936) connecting between the areas in the fluid holding chamber partitioned by the volume changing means; and an elastic member of annular shape (8a, 8b), arranged between the resistance generating member and the fluid holding chamber; the elastic member (8a, 8b) comprising: an inner peripheral surface having a width in a direction of a center axis of the fluid holding chamber and being pressed against the resistance generating member; and an outer peripheral surface having a width in the direction of the center axis of the fluid holding chamber and being pressed against the fluid holding chamber, an inner peripheral surface having a width in a direction of a center axis of the fluid holding chamber and being pressed against the resistance generating member; and an outer peripheral surface having a width in the direction of the center axis of the fluid holding chamber and being pressed against the fluid holding chamber, wherein the width, in the direction of the center axis of the fluid holding chamber, of the inner peripheral surface of the elastic member (8a, 8b) is smaller than the width, in the direction of the center axis of the fluid holding chamber, of the outer peripheral surface of the elastic member (8a, 8b), characterised in that the elastic member (8a, 8b) comprises: an inner periphery side annular portion having a rectangular cross section and including the inner peripheral surface of the elastic member (8a, 8b); an outer periphery side annular portion having a rectangular cross section and including the outer peripheral surface of the elastic member (8a, 8b); and a coupling portion connecting between the inner periphery side annular portion and the outer periphery side annular portion, the coupling portion having a width smaller than the widths (t6, t7) of the inner periphery side annular portion and the outer periphery side annular portion, in the direction of the center axis of the fluid holding chamber. an inner periphery side annular portion having a rectangular cross section and including the inner peripheral surface of the elastic member (8a, 8b); an outer periphery side annular portion having a rectangular cross section and including the outer peripheral surface of the elastic member (8a, 8b); and a coupling portion connecting between the inner periphery side annular portion and the outer periphery side annular portion, the coupling portion having a width smaller than the widths (t6, t7) of the inner periphery side annular portion and the outer periphery side annular portion, in the direction of the center axis of the fluid holding chamber.