To provide a viscous fluid-sealed damper which helps to achieve an increase in degree of freedom in terms of selection of material of a sealing container, which can be produced with high production efficiency, and which helps to avoid leakage of the viscous fluid.

A lid member 18 is fixed to a container main body 16 while compressing and holding a flange portion 22 between a sealing member 17 and the lid member 18, so an opening end 16a of the container main body 16 can be sealed with the lid member 18 without having to effect fixation through fusion-bonding as in the prior art, and the degree of freedom in terms of material selection can be increased. Further, if the container main body 16 is formed of butyl rubber, the container main body 16 can be fixed to the lid member 18 without using any adhesive, so it is possible to achieve a reduction in production time and in cost. Further, it is possible to avoid leakage of the viscous fluid 10 due to defective adhesion.