PURPOSE: To make an eccentric cam thin so as to reduce bending stress generated to an eccentric cam holding part.

CONSTITUTION: A lower arm bracket 18 for supporting the lower arm of a suspension is fixed to each end part lower wall part 14A of a rear cross member 14 by arc welding. A pair of opposed retainers 26, 36 are respectively formed at the rear cross member 14 and the lower arm bracket 18, and the peripheral edge parts 44A of eccentric cams 44 fitted to both end parts of a lower arm fitting bolt 42 are held to the contact faces 26A, 36A of the respective retainers 26, 36. The retainer 26 side end part of the base part 18A of the lower arm bracket rear 18 is provided with a recessed part 38 formed on the opposite side to the eccentric cam 44, and the retainer 36 side end part of the front wall part 14A of the rear cross member 14 is provided with a recessed part 40 formed on the opposite side to the eccentric cam 44.