A folding mechanism for a treadmill having a main frame, a platform and a shaft mounted on the main frame. The main frame is adapted for mounting a motor to impart rotary motion to a worm. Meanwhile, the main frame is rigidly connected to a base frame having an sliding groove or rail with an open side. The platform includes front and rear rollers on the under surface thereof. The front rollers are slidably fitted in the sliding rail. The shaft is mounted on the main frame while a yoke with a crossbar and two supporting arms is rotatably mounted on the shaft. The crossbar includes a worm wheel engaging with the worm, and the free end of the supporting arms is pivotally connected to both sides of the platform. Based on the above-mentioned, the treadmill's platform can be lifted in an inclined position. Furthermore, a locking element is employable to fold the platform in a storage position.
