A synthetic polymer membrane (34A) and (34B) having a surface having a plurality of convex portions (34Ap) and (34Bp), when viewed from the normal direction of the synthetic polymer membranes (34A) and (34B) The two-dimensional size of the plurality of protrusions (34Ap) and (34Bp) is in the range of more than 20 nm and less than 500 nm, the surface has a bactericidal effect, and the concentration of nitrogen element contained in the surface is 0.7 at % Or more.複数の凸部（３４Ａｐ）、（３４Ｂｐ）を有する表面を備える合成高分子膜（３４Ａ）、（３４Ｂ）であって、合成高分子膜（３４Ａ）、（３４Ｂ）の法線方向から見たとき、複数の凸部（３４Ａｐ）、（３４Ｂｐ）の２次元的な大きさは２０ｎｍ超５００ｎｍ未満の範囲内にあり、表面が殺菌効果を有し、表面に含まれる窒素元素の濃度が０．７ａｔ％以上である。
