To improve strength in a joint part of a trailing arm part and a lateral link part in a suspension arm.

The lower arm (suspension arm) is equipped with the trailing arm and the lateral link part composed of a separate member. The lateral link part is composed of a hollow pipe, and crushed so that the cross section becomes a vertically long ellipse. The lateral link part has a joint part 10c capable of face contacting with the outer peripheral surface of the rear end 10b1 of the trailing arm part at the outer end 20b. The joint part 20c is composed of a welding part 20c1 of the front side and a welding part 20c2 of the rear side. The welding part 20c1 of the front side and the welding part 20c2 of the rear side are formed in a curved shape.