PROBLEM TO BE SOLVED: To provide a polymer composition which minimizes a risk associated with embolization. A polymer composition comprising a biocompatible polymer having a biodegradable bond to a visualization agent and a non-physiological solution, wherein the biocompatible polymer is soluble in the non-physiological solution. A polymer composition that is insoluble in physiological solutions. [Selection diagram] Figure 2【課題】塞栓形成に関連している危険を最小限に抑えるポリマー組成物の提供。【解決手段】可視化剤への生分解性結合を有する生体適合性ポリマーと、非生理溶液と、を含むポリマー組成物であって、前記生体適合性ポリマーが、前記非生理溶液には溶解するが生理溶液には溶解しない、ポリマー組成物。【選択図】図2