PROBLEM TO BE SOLVED: To provide a method that can stabilize medical protein susceptible to modification, facilitates its concentration and storage, and easily gets the protein back into the original state at the time of administration.SOLUTION: A complex of a medical protein and an α-helix structure of a polyamino acid stabilizes the protein as compared to a complex with a random structure of the polyamino acid, and also has better stability during its transportation and storage, and better handleability during its use.SELECTED DRAWING: Figure 1【課題】変性しやすい医療用タンパク質をより安定化でき、濃縮、保存等が容易で、投与するときは容易に元のタンパク質にできる方法を提供しようとする。【解決手段】医療用タンパク質とポリアミノ酸のαへリックス構造との複合体は、ポリアミノ酸のランダム構造との複合体より、当該タンパク質がより安定化でき、輸送時や保存時の安定性に優れ、用時の取り扱い性に優れる。【選択図】図1