An allergen reduction agent having an allergen reduction function against mite and pollen etc. is provided, wherein the allergen reduction agent includes a polymer or a copolymer of a terpenoid which serves as an active ingredient and is capable of suppressing coloration.提供一種過敏原降低劑,其具有對蟎和花粉等過敏原降低功能,且該過敏原降低劑以能夠抑制著色的萜類的聚合物或共聚合物作為有效成分。