A seat back suspension assembly for a vehicle, disposed in a seat back frame inside a vehicle seat, may include a main wire including side wires extending in a vertical direction at left and right side thereof; at least one first support wire extending in a horizontal direction between the side wires at both sides thereof to allow both ends thereof to contact the side wires; at least one second support wire disposed to be spaced from the first support wire and extending in a horizontal direction between the side wires at both sides thereof to allow both ends thereof to contact the side wires; and a side guide injection-molded to cover the side wire and end portions of the first and second support wires contacting the side wire.

A seat back suspension assembly for a vehicle, disposed in a seat back frame inside a vehicle seat, may include a main wire including side wires extending in a vertical direction at left and right side thereof; at least one first support wire extending in a horizontal direction between the side wires at both sides thereof to allow both ends thereof to contact the side wires; at least one second support wire disposed to be spaced from the first support wire and extending in a horizontal direction between the side wires at both sides thereof to allow both ends thereof to contact the side wires; and a side guide injection-molded to cover the side wire and end portions of the first and second support wires contacting the side wire.