To provide a blind nut for increasing fitting reliability.

This blind nut, fittable by work from only one side of a plate body, is composed of a collar 1 composed of a tube part 11 and a flange part 12 swollen to one end outer periphery of the tube part 11, and a nut having the outer diameter larger than the inner diameter of the tube part 11; the collar 1 is fitted into a fittedly engaging hole provided on the plate body, and the nut is press fitted into the tube part 11 to expand it to nip the plate body by the expanded tube part 11 and the flange part 12, thereby fitting the blind nut to the plate body.