<;P>;PROBLEM TO BE SOLVED: To provide an odor treatment method and system, and a rearing system which can economically treat odors. <;P>;SOLUTION: Nanobubbles of nitrogen gas are introduced into washing water stored in a washing water tank 5. The washing water containing the nanobubbles and nitrate ions generated by oxidation of the nitrogen gas of the nanobubbles is sprayed onto a source of odors to wash away the source of odors. The washing water sprayed onto the source of odors is recovered into the washing water tank 5. Odor substances and an organic matter are decomposed, and at the same time odors emitted from the source of odors are removed by water films 24 and a scrubber 4. <;P>;COPYRIGHT: (C)2009,JPO&INPIT