Abstract: A folding device for a scooter includes a base plate, a head tube, a handlebar stem, a support rod, and a support base. The support base includes a first side plate and a second side plate, an arcuate slide track defined in the first side plate, and a first locking hole and a second locking hole respectively defined in the second side plate. The support rod includes a transverse tube pivotally mounted between the first side plate and the second side plate and a receiving chamber located above the transverse tube for receiving a support tube. A pull rod is slidably mounted in the support tube and has a first end provided with an outer thread slidably mounted in the slide track and engaged with a pull knob and a second end provided with an enlarged head detachably received in the first locking hole or the second locking hole. A guard plate is mounted for supporting the support rod, and a retaining piece is pivotally mounted on the guard plate for retaining the support rod.