To obtain an inexpensive, silent cooling apparatus of gas-filled electrical equipment by making a casing of a first heat exchange with a thick sound insulating material and providing a cooling piping for circulation of a cooling liquid within the casing.

This cooling equipment includes gas-filled electrical devices 3 and 4 housed in a gas-sealed container, a first heat exchange 9 for transmitting a thermal energy of a sealing gas 2 sealed into the gas-filled electrical devices to a cooling liquid, a second heat exchange 12 having a circulating pump for externally dispersing the thermal energy of the cooling liquid, a first cooling pipe line 7 having a circulating pump for circulating the sealing gas of the gas-filled electrical devices for heat exchange with the first heat exchange, a second cooling pipe line 10 for circulating the cooling liquid between the first and second heat exchanges, and a cooling piping provided within sound- insulating casing for passage of the cooling liquid through the interior of the casing.