Provided are a novel Dermatophagoides farinae protein, and a diagnostic drug, a prophylactic drug and a therapeutic drug for an allergic disease caused by Dermatophagoides farinae.A Dermatophagoides farinae protein selected from the group consisting of the following (a) to (c), or a fragment peptide thereof:(a) a protein including an amino acid sequence set forth in SEQ ID NO:2；(b) a protein including an amino acid sequence in which one or several amino acids have been substituted, deleted, or added relative to the amino acid sequence set forth in SEQ ID NO:2, and having allergenicity of Dermatophagoides farinae； and(c) a protein including an amino acid sequence having 90% or higher identity with the amino acid sequence set forth in SEQ ID NO:2, and having allergenicity of Dermatophagoides farinae.
