Abstract: A full floating device of a rear seat cushion for an automobile comprises a fixed frame fixed on a floor panel of the automobile, a pivot frame to which the end of the supporting bracket is linked by a pivot pin and on which a seat cushion is mounted, and an angle adjusting means pivoting the rear end of the pivot frame about the pivot pin in order to adjust the inclination of the seat cushion mounted on the pivot frame. The device in accordance with the present invention can adjust the angle of the rear seat cushion of the automobile according to the condition of the passenger, and the passenger can be comfortable.