To increase rigidity and strength in a peripheral region of a bolt connecting part, facilitate inserting of a member into between both interposition fixed pieces.

In almost the central part of a plate-shaped member, almost C-shaped clamp fixed part 17 is formed, both end parts are extended so as to be almost in parallel to each other, and a pair of interposition fixed pieces 18, 18 are formed. A suspension strut 11 is clamp fixed by the clamp fixed part 17, between the interposition fixed pieces 18, 18, a knuckle 16 is inserted, to be fixedly tightened by a bolt 21 and a nut 22. In a part serving as a seat for the bolt 21 and the nut 22 of the interposition fixed piece 18, a recessed part 23 hollowed in a direction narrowing a space of the interposition fixed pieces 18, 18 is formed. By the recessed part 23, rigidity and strength are enhanced. By contact with the knuckle 16 by the recessed part 23, an end part mutual space of the interposition fixed pieces 18, 18 is spread, and an inserting property of the knuckle 16 is enhanced.