Abstract: Provided is a composite membrane for western blot, in which the composite membrane is prepared by combining nanofiber webs with nonwoven fabrics, and a basis weight of the nanofibers is in a range of 1 gsm to 50 gsm on the nonwoven fabrics, and an average pore size is in a range of 0.1 ?m to 1.0 ?m. The composite membrane for western blot including nanofibers has advantages such as saving of a production cost, and an excellent response characteristic due to a capillary phenomenon of a double structure, to thereby easily detect even a small amount of a particular substance present in a protein.