Ball joint assembly for vehicle and manufacturing method thereof

A ball joint assembly for a vehicle includes a ball stud (10) having a ball (13) on a shaft (11), a pair of bearing members (30) in sliding contact with the ball of the ball stud, a seat member (50) supporting an exterior circumference of the bearing members, and an outer case (70) enclosing the seat member. According to the ball joint assembly for a vehicle, the outer case (70) and the bearing members (30) are separately provided, and the seat member (50) is formed of a molding portion insert-molded between the outer case and the bearing members.