Abstract: In the vibration isolation device for a cogeneration system with an engine, to suppress vibrations and noise from the engine, the mounting table on which the engine and the generator are mounted is installed through the main tires and the subtires on the base laid at the installation site. The support members arranged on the base are made to contact the main tires and the subtires and are secured to the base. Further, the sound isolation device for a cogeneration system has a truck--comprising the mounting table and the tires--mounted on the base placed in the installation chamber at the installation site. The installation chamber is formed by multilayer wall bodies. The multilayer wall bodies each comprise a hollow metal housing, a rubber covering layer secured to the inner surface of the metal housing, and a corrugated support member incorporated in the metal housing. The multilayer wall bodies have their hollow portions evacuated.