Front lower arm

1. A front lower arm tiltably supported, in a cantilever manner, by an outer surface of each of side-rails respectively provided in right and left regions of a vehicle in a vehicle right-left direction, the side-rails extending in a vehicle front-rear direction, the front lower arm comprising:

a lower arm body;

an inner pivot provided at an inner end of the lower arm body in the vehicle right-left direction, the inner pivot being supported by a corresponding one of the side-rails; and

an attachment portion to which a lower end of a shock absorber is attached, the attachment portion being joined to an intermediate section of a front upper corner portion of the lower arm body, the front upper corner portion of the lower arm body being an upper corner portion at a front of the lower arm body in the vehicle front-rear direction, and the intermediate section being an intermediate section of the front upper corner portion in the vehicle right-left direction, wherein

the front lower arm is configured such that a ball joint to which a knuckle is connected is attached to an outer end of the front lower arm in the vehicle right-left direction,

the attachment portion has a rectangular tubular shape and includes a first wall, a second wall, a third wall, and a fourth wall, the first wall and the second wall facing each other and extending in the vehicle right-left direction, the second wall being disposed rearward of the first wall in the vehicle front-rear direction, the third wall and the fourth wall facing each other and extending in the vehicle front-rear direction, and the fourth wall being disposed inward of the third wall in the vehicle right-left direction,

the first wall is disposed forward of the front upper corner portion of the lower arm body in the vehicle front-rear direction such that the first wall is spaced apart from the front upper corner portion.

2. The front lower arm according to claim 1 , wherein:

at least a lower end portion of the second wall, a lower end portion of the third wall, and a lower end portion of the fourth wall are joined to the front upper corner portion; and

a lower end portion of the second wall is provided with a cutout.

3. The front lower arm according to claim 1 , further comprising a ball joint bracket to which the ball joint is attached, the ball joint bracket being joined, by welding, to an outer end of the lower arm body in the vehicle right-left direction, wherein

the lower arm body is formed in a box shape by assembling together an upper plate member and a lower plate member, and an outer side portion of the lower arm body in the vehicle right-left direction is provided with an opening,

the ball joint bracket is a forged product,

an inner end portion of the ball joint bracket in the vehicle right-left direction has such an outer shape that the inner end portion of the ball joint bracket is fitted in the opening of the lower arm body, and

the lower arm body and the ball joint bracket are joined to each other by inserting the inner end portion of the ball joint bracket into the opening of the lower arm body and welding an outer periphery of the inner end portion of the ball joint bracket to an end face of the lower arm body, which defines the opening of the lower arm body.