A suspension arm includes a bottom wall, a first side wall and a second side wall that protrude upward from the bottom wall and face each other, and an airflow guide section that extends from the first side wall in a direction away from the second side wall. The first side wall includes a base end and a distal end. The base end is closer to the bottom wall in a protruding direction in which the first side wall protrudes from the bottom wall. The distal end is away from the bottom wall in the protruding direction. The airflow guide section extends from a portion of the first side wall between the base end and the distal end.