A mounting member is improved in durability, allows an article to be mounted at a desired position of a structure and eliminates the necessity of a special mechanism for preventing rotational movement of a fastening member. The mounting member has a fattened or stepped portion formed adjacent each of a pair of transverse crossing or corner portions defined between flanges and webs thereof for preventing rotational movement of the head of a fastening member disposed within a groove defined by means of the webs and the flanges. If the head of a fastening member is inserted into the groove through means of an opening defined between the flanges and then the fastening member is rotated through means of an angle of approximately 90 degrees about its axis within the groove, the head of the fastening member is interposed between the fattened portions and prevented from rotating about its axis.