<p>It is intended to provide a protease inhibitor which contains as the active ingredient a protein selected from the group consisting of SCCA1, SCCA2 and variants thereof. Because of having an effect of inhibiting the protease activity of Der pl which is a mite allergen, the above protease inhibitor inhibits not only a synthetic peptide serving as a substrate but also the activity of Der pl of cutting CD25 antigen on the T cell surface layer. Thus, this protease inhibitor is useful in treating mite allergy. It is also intended to provide a screening method with the use of the expression or activity level of SCCA1 or SCCA2 as an indication. A compound thus screened is useful as a remedy for mite allergy.</p>
