A knuckle is minimized in size to be located in an internal space of a rear wheel. An upper arm is disposed lower than a conventional double wishbone type and one end of the upper arm is secured to the knuckle. A shock absorber couples at a lower end thereof to the knuckle by passing through a space between a lower arm and assist arm. This configuration thus constructed greatly increases the space of the trunk room, reduces noise by minimizing the transmission of road impact and vibration, and improves ride comfort as well as braking stability and turn stability.