A steering wheel of a vehicle includes a steering wheel armature made of metal, a steering wheel rear cover made of plastic, and an airbag module. The steering wheel rear cover is located on a bottom of the steering wheel armature and the airbag module is mounted above the steering wheel armature. An Ω spring assembles the airbag module onto the armature. At least a supporting rib extends from the steering wheel rear cover and is located between the Ω spring and the steering wheel armature for supporting the Ω spring. The supporting rib erases a gap between the Ω spring and the steering wheel armature and it is formed by plastic, thereby reducing noise efficiently.