A base insulating layer in an FPC board is used as a fuel supply amount adjustment film for a fuel cell. The base insulating layer in the FPC board has a plurality of anisotropic through pores. The anisotropic through pores respectively has openings on one surface and the other surface of the base insulating layer. The respective openings on the one surface and the other surface of the base insulating layer communicate with each other without diverging by a single communication path. The communication path has a shape that can specify a long axis and a short axis perpendicular to the long axis. The long axis extends in a direction intersecting the one surface and the other surface of the base insulating layer at a predetermined angle.