The present invention discloses direction correcting apparatus and method thereof for a movable radiation inspecting system having a moving device. The direction correcting apparatus comprises: a direction detecting device for detecting a moving direction of the moving device and generating a detecting signal indicating the moving direction; a direction control device for controlling the moving direction of the moving device; and a control unit for calculating a deviation value between the moving direction and the predetermined direction based on the detected signal received from the direction detecting device, and the direction control device is driven according to the deviation value to correct the moving direction to the predetermined direction. The direction correcting apparatus according to the present invention can automatically control the movable radiation inspecting system to move linearly in a predetermined direction during working, which enhances automatic control degree, and has a simple structure with installing easily and reduced cost. And it also does not influence the normal running of the inspecting system on a road while not inspecting.