To hardly damage fibers and eliminate a pool on a floor and the shrinkage of a product by suppressing the amount of water used while effectively killing organisms creeping even into the depth of the fibers of a carpet.

A diluted solution containing about 50% bio-detergent [BLAST OFF (R)], formed of a natural amino acid and natural polymeric polysaccharides and capable of decomposing foulings by a biochemical reaction is sprinkled over a carpet and 10-15min standby time is placed. During the time, the foulings are decomposed by the biochemical reaction. The carpet is then treated under a vacuum while discharging steam at about 60°C only for ≤5 sec time. Since the cleaning is carried out simply by decomposing and sucking the foulings, fibers are not damaged and the amount of water used is small.