Filter medium and composite filter including same

A composite filter comprising a filter medium, wherein the filter medium comprises:

• a first porous support body which has been electrostatically treated and is a melt blown non-woven fabric configured to use an electrostatic force to filter dust contained in air;
• a water- and oil-repellent nanofiber web which is disposed on one surface of the first porous support body and formed by accumulating nanofibers, wherein the nanofiber web has an average pore diameter of 0.3 to 2.5 μm, and an air permeability of 4 to 35 cfm;
• a second support body disposed between the first porous support body and the water- and oil-repellent nanofiber web, which is a thermal bonding non-woven fabric which performs a support function;
• a third support body disposed on an opposite surface of the first porous support body corresponding to a side of the second support body, which is a water- and oil-repellent spunbonded non-woven fabric;
• and
• a fourth support body disposed on an opposite surface of the nanofiber web corresponding to a side of the second support body, which is a spunbonded non-woven fabric that prevents damage during bending.