To provide an origin detection method capable of shortening a time required for origin detection work of a pair of screw nuts 21a, 21b that slide when changing a camber angle in a double wishbone type suspension device for vehicle.

Which a wheel posture is set to between a positive camber and a negative camber is determined by rotatingly driving an electric motor 11 slightly in both directions to compare magnitudes of motor current in respective cases, and which side screw nuts 21a, 21b are located on is specified with respect to a neutral position where a camber angle is a zero degree. A movement direction for moving the screw nuts 21a, 21b toward the origin is determined on the basis of the specified side. Then, the screw nuts 21a, 21b are moved until an origin detection sensor 41 supported by a frame 9 detects an origin mark 42 formed on an external peripheral surface of a guide cylinder 24a.