PROBLEM TO BE SOLVED: To provide a pharmaceutical combination comprising a heat shock protein 90 (Hsp90) inhibitor and an HER2 inhibitor, and a method of using the combination, which are effective in treatment of proliferative disorders such as breast cancer.SOLUTION: The present invention provides a pharmaceutical combination in which the HER2 inhibitor is trastuzumab and the Hsp90 inhibitor is a compound represented by the formula in the figure, and a method of using the combination. [Ris CHCHNHC(=O)- or (CH)CHNHC(=O)-)； Ris ethyl, isopropyl or the like； Ris -CHNRRor -NRR； and -NRRis morpholinyl or the like.]【課題】乳癌等の増殖性障害の治療に有効な、熱ショック蛋白質９０（Ｈｓｐ９０）阻害剤及びＨＥＲ２阻害剤を含む医薬品の組合せ、及び該組合せを使用する方法の提供。【解決手段】ＨＥＲ２阻害剤がトラスツズマブであり、Ｈｓｐ９０阻害剤が下記式に代表される化合物である医薬品の組合せ、及び該組合せを使用する方法。［Ｒ３はＣＨ３ＣＨ２ＮＨＣ（＝Ｏ）－又は（ＣＨ３）２ＣＨＮＨＣ（＝Ｏ）－）；Ｒ８はエチル、イソプロピル等；Ｒ９は－ＣＨ２ＮＲ１０Ｒ１１又は－ＮＲ１０Ｒ１１；－ＮＲ１０Ｒ１１はモルホリニル等］【選択図】なし
