An embodiment of the present invention provides a roller shade actuation device for actuating a winding drum with an outer surface mounted with an end of a shade body. Opposite ends of the winding drum are rotatably mounted to corresponding frames with the help of pivots. The roller shade actuation device is mounted between one of the frames and the winding drum. The roller shade actuation device includes a middle shaft rotatably mounted to an inner sidewall of the frame, and a plane scroll spring mounted outside the middle shaft and axially parallel to the middle shaft. The middle shaft is connected to a pivot of a corresponding end of the winding drum through shaft connection. An outer end of a reed of the plane scroll spring is fixed to an outer surface of the middle shaft.