To provide a decorative nut and bolt with an antitheft function capable of making an attaching area of a decorating seal same as that of other nuts or bolts.

An outer circumferential face 1d of a nut body 1 with the decorative seal 3 attached to a top face 1b is cylindrically shaped, and a plurality of arced key protruding parts 2 are formed in a screw hole 1a opening end side outer circumferential face of the cylindrical outer circumferential face 1d with different patterns in size, circumferential positions or the like between each set commodity. A head outer circumferential face 5b of a bolt body 5 with the decorative seal 3 attached to a top face 5a is cylindrically shaped, and a plurality of arced key protruding parts 2 are formed in a screw part 5c side end part outer circumferential face of the cylindrical outer circumferential face 5b with different patterns in size, circumferential positions or the like between each set commodity.