To prevent the slackness of a female screw engaged with a male screw portion of a shaft in a connecting structure relatively rotatably connecting a first member and a second member on the shaft.

A bolt 14 (shaft) is press-fitted into a movable bracket 13 (first member). A groove 14b is formed on the outer periphery of the male screw portion 14a of the bolt 14. A bush 17 (second member) is press-fitted into a lower arm 12, the bolt 14 is rotatably inserted into the inner cylinder 17b of the bush 17. A convex portion of a plate 18 is assembled to the groove 14b of the bolt 14 in a connected state in the male screw portion 14a of the bolt 14 extending from the inner cylinder 17b of the bush 17. The plate 18 is fastened by a flange nut 19. The slackness of the flange nut 19 against the male screw portion 14a of the bolt 14 is prevented so that the movable bracket 13, the bolt 14, the plate 18, and the flange nut 19 relatively rotate to the bush 17.