Abstract: An automobile antenna fastening device comprising an inner fastening assembly and outer fastening assembly. The inner fastening assembly includes a gland washer made of an elastic material and a gland base, and the outer fastening assembly includes a pad and fastening nut. An antenna is mounted on the automobile body wall by clamping the automobile body wall between the outer and inner fastening assemblies, and the clamping force of the fastening assemblies is maintained by the elastic deformation of the gland washer of the inner fastening assembly.