[Problem] Provided is a decontamination system which does not require large scale equipment such as large diameter ducts or anti-condensation heaters, while enabling, with respect to a plurality of rooms targeted to be decontaminated, pipelining of which distance is long for each room, the decontamination system being capable of supplying an accurate amount of decontamination gas for each room.[Solving Means] Compressed air-generating means and decontamination solution-supplying means are included, mixed gas-liquid adjusters and gas generators are respectively provided in each room targeted to be decontaminated, and a conveyance distance of gas-liquid supplying pipes which communicate with the mixed gas-liquid adjusters and the gas generators is longer than a conveyance distance of decontamination solution supplying pipes which communicate with decontamination solution-supplying means and the mixed gas-liquid adjusters.