The present invention has an object of providing a cushioning device having a stable and superb vibration-damping property and a metal cover attachable by use of the cushioning device. A cushioning device, which is to be located between an exhaust manifold as a vibration source and a heat insulator as a connection target and connects the exhaust manifold and the heat insulator to each other and cushions transmission of a vibration from the exhaust manifold to the heat insulator, includes a multi-stage coiled and spiral spring for cushioning the vibration, a grommet for joining the multi-stage coiled and spiral spring and the heat insulator to each other, and a collar member located between an attaching bolt tightened to the exhaust manifold and the multi-stage coiled and spiral spring. The multi-stage coiled and spiral spring is formed of a wiring member having a spiral shape as seen in a plan view.