PURPOSE: To decrease the occurrence of knee action of a spring used in the suspension system.

CONSTITUTION: Wheels 6 are rotatably supported by an axle carrier 5, and an upper arm 1 and a lower arm 2 each of A type vertically rotatably connected to a vehicle body via ball joints 10, 12, respectively, are mounted to the axle carrier 5: The lower arm 2 is provided with a spring seat 23 whose seat surface 24 is inclined toward the inside of the vehicle. A spring seat 21 whose seat surface 22 is directed toward the spring seat 23 of the lower arm 2 is provided at an intermediate portion of a bush 7 of the upper arm 1. A coil spring 4 is provided between the spring seat 21 and the spring seat 23.