A medical instrument according to the present invention is provided with a base material that comprises a fluorinated cyclic olefin polymer containing a structural unit represented by general formula (1), said medical instrument being characterized in that the base material has one surface through which cells can contact with the material, the base material has a convex/concave structure on the aforementioned surface, the ratio of the distance (L1) between convex parts formed in the convex/concave structure to the largest diameter (L2) of each of the seeded cells, i.e., (L1/L2), is 1 to 300, the cells cannot adhere or attach to the aforementioned surface having the convex/concave structure formed thereon, and the medical instrument can enhance the proliferation of cells. (In formula (1), at least one of R1 to R4 represents a fluorine atom, an alkyl group having 1 to 10 carbon atoms and containing a fluorine atom, an alkoxy group having 1 to 10 carbon atoms and containing a fluorine atom, or an alkoxyalkyl group having 2 to 10 carbon atoms and containing a fluorine atom, wherein R1 to R4 are independently selected from a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, and an alkoxyalkyl group having 2 to 10 carbon atoms when each of R1 to R4 represents a group containing no fluorine atom, R1 to R4 may be the same as or different from one another, and R1 to R4 may be bonded to one another to form a cyclic structure.)本發明之醫療器具係具備使用含有通式(1)所表示之構造單位之含氟環狀烯烴聚合物之基材者，其特徵在於：上述基材具有使該基材與細胞接觸之一面，且該基材於上述一面具備凹凸構造，由上述凹凸構造構成之凸凸間之寬度(L1)與上述細胞中之每一播種細胞之最大直徑(L2)之比(L1/L2)為1~300，且不使上述細胞接著或附著於具備上述凹凸構造之上述一面而促進細胞增生。(式(1)中，R1~R4中之至少1個為氟、含有氟之碳數1~10之烷基、含有氟之碳數1~10之烷氧基、或含有氟之碳數2~10之烷氧基烷基。於R1~R4為不含氟之基之情形時，R1~R4為選自氫、碳數1~10之烷基、碳數1~10之烷氧基、或碳數2~10之烷氧基烷基。R1~R4可相互相同亦可不同。又，R1~R4亦可相互鍵結而形成環構造)
