PROBLEM TO BE SOLVED: To provide a method of inhibiting or reducing deregulated FMS-like tyrosine kinase 3 (FLT3 kinase) activity or expression, the method used for treating or preventing proliferative disorders such as leukemia, myeloma, and myeloproliferative disorder.SOLUTION: The present invention provides a method for administering crenolanib represented by the formula, or pharmaceutically acceptable salt or solvate thereof.SELECTED DRAWING: None【課題】脱制御化した、FMS様チロシンキナーゼ3(FLT3キナーゼ)の活性又は発現を阻外又は低下させる方法で、白血病、骨髄腫、骨髄増殖性疾患等の増殖性疾患の治療又は予防方法の提供。【解決手段】下式に示されるクレノラニブ又はその医薬的に許容される塩もしくは溶媒和物の投与する方法。【選択図】なし