In a cell-capturing filter including a metal porous membrane, degradation over time is determined earlier. A cell-capturing filter includes a metal porous membrane having a plurality of through-holes that penetrate between two principal surfaces facing each other. The metal porous membrane is made of an alloy of nickel and an element selected from the group consisting of gold, platinum, and palladium, or a metal containing nickel as a main component. A metal containing copper as a main component is attached to a part of either one of the principal surfaces of the metal porous membrane. By checking a state change of the metal containing copper as a main component, degradation over time of the metal porous membrane can be determined earlier