A step device mounts on the tailgate of a truck to pivot downwardly and rearwardly from the open tailgate in a working position for providing easier access to the truck box. The step device includes a base fastened onto the tailgate upon which two rails are slidably mounted between retracted and extended positions. A pair of legs are pivotally coupled to rear ends of the respective rails and are joined by a step member opposite the pivoted ends. The base is fully unobstructed between the rails and the area between the legs is fully unobstructed above the step member to remove any tripping hazards in use.