PROBLEM TO BE SOLVED: To provide an allergen deactivator having a plant extract as an active ingredient and an allergen deactivating material provided with a carrier holding the plant extract.SOLUTION: An extract from a leaf portion of Kohki (scientific name is Engelhardtia chrysolepis Hance) and/or an extract from a leaf portion and a stem portion of Lemon balm (scientific name is Melissa officinalis) is contained as the active ingredient of the allergen deactivator. The allergen deactivating material contains the carrier, the extract from the leaf portion of Kohki held by the carrier and/or the extract from the leaf portion and the stem portion of the Lemon balm.