To provide a nut with a spring washer and a bolt and nut fastening method to prevent the generation of refuse after a fastening work, simplify fastening torque management, and reduce a cost.

This nut with a spring washer 8 comprises a nut 2; a spring washer 3; and a film 6 to cover the peripheries of the nut 2 and the spring washer 3 such that an upper edge part 4 and a lower edge part hook respectively the upper surface peripheral edge 2a of the nut 2 and the under surface peripheral edge 3a, of the spring washer 3. The nut with the spring washer 8 has at least one line for discrimination 7 which extends along the radial directions of the nut 2 and the spring washer 3, in a position above the lower edge part of the film 6. By threaded by engaging and regularly fastening, the nut 8 with the bolt 1 a prescribed range above the lower edge part of the film 6 is whitened at the time when a fastening work is completed, and a part 7a of the line for discrimination contained in the given range is inclined as it is stretched from a position extending along the radial directions of the nut 2 and the spring washer 3.