To effectively suppress the vibration of an rotary machine such as servomotor without dispersing dust and the like outside.

The hermetically sealed type damper is formed out of an annular container 4 which is fixed to the rotating shaft 3 of a rotary machine 1, and is made out of non-magnetic material, a magnetic body 5 hermetically sealed inside the annular container 4 in such a way as to be freely moved, and of a plurality of permanent magnets 6 which are arranged over the circumference faced to the outer circumferential surface of the annular container 4 of the rotary machine 1 so as to be fixed thereto. Since the magnetic body 5 is restricted by magnetic fields generated by the permanent magnets 6, when the rotating shaft 3 is vibrated, the magnetic body 5 starts a relative movement with respect to the annular container 4. Vibration can thereby be absorbed by friction provided at the time.