Provided is a metallic glass fastening screw that is added with the property not susceptible to loosening, and is capable of implementing fastening with high strength and reliability in lightweight members and other members in various fields. In processing a screw thread and a screw groove of a screw, amorphous bulk metallic glass is form-rolled at glass transition temperature or less of the bulk metallic glass as a process material. The bulk metallic glass has the property that plastic strain is introduced by plastic working such as form rolling, so as to improve ductility in a region including a slip band. By effectively using this property, a relationship of d >； 0.022 x D is made to hold provided that a depth from a bottom of the screw groove in the region where the plastic strain is introduced by the form rolling is d and an outside diameter of the screw is D, in order to relax stress concentration of tensile stress generated in a region at the bottom of the screw groove due to tension (axial force) applied to the screw in fastening.
