A synthetic polymer film (34A), (34B) that is provided with a surface that has a plurality of protrusions (34Ap), (34Bp). When seen from the normal direction of the synthetic polymer film (34A), (34B), the two-dimensional size of the plurality of protrusions (34Ap), (34Bp) is greater than 20 nm but less than 500 nm. The surface has bactericidal effects, and the nitrogen concentration in the surface is 0.7 at% or more.本發明之合成高分子膜(34A)、(34B)具備具複數個凸部(34Ap)、(34Bp)之表面,且於自合成高分子膜(34A)、(34B)之法線方向觀察時,複數個凸部(34Ap)、(34Bp)之二維大小處於超過20nm且未達500nm之範圍內,表面具有殺菌效果,表面中所含之氮元素之濃度為0.7at%以上。