| abstract |
A filter medium comprises a modified cross-section fiber (A) having a fiber diameter between 40 and 70 μm, an extremely fine fiber (B) having a fiber diameter of more than 5 μm and no more than 10 μm and a modified cross-section fiber (C) having a fiber diameter between 15 and 30 μm, the content of the extremely fine fiber (B) is between 3 and 10% by mass, and the content of the modified cross-section fiber (C) is between 5 and 15% by mass based on 100% by mass of total the fibers in the filter medium. |