To prevent peeling-off of a coating film or a plating layer in an edge of a bolt or a nut or in its vicinal part, when fastening or loosening a face bolt or a face nut, that is, a painted or plated bolt or nut by a rotating socket.

This protective tool of the bolt or the nut in the socket for rotating the bolt or the nut, is composed of a top plate part 27 and a side part 29 continuing with the top plate part, and is characterized by integrally forming a substantially polygonal body suitable for being fitted around a bolt head 13 or the nut 15 out of a flexible material. A through-hole 33 is desirably provided in the top plate part. A hard plate 47 is desirably installed on the whole outside surface of the side part.