PURPOSE: To reduce the man-hour for mounting a vibration prevention member and to facilitate simple automation by employing the vibration prevention member made of a gelable liquid material.

CONSTITUTION: An oscillator 2 is put on a vibration preventing member 1 and the surrounding part is surrounded by box shaped side plates 3 acting like an electromagnetic wave shield plate. A two liquid mixture material is injected between the oscillator 2 and the side plates 3 and all the surrounding parts are packed. That is, a two-liquid mixture vibration prevention member 4 formed to be a gel after a prescribed time is formed by injecting a liquid material generated by mixture of two liquids to the surrounding of the oscillator 2 accommodated in the box. Thus, the vibration prevention member in which the liquid material is changed in a gel is used to reduce the mount process of the two- liquid mixture vibration prevention member 4 and since only the liquid injection is required for the work, automation is implemented simply and the work man- hour is considerably reduced.