This paper proposes an innovative method to employ a ducted-fan propulsion system to drive the legs of a bipedal robot, named Jet-HR1 (Jet Humanoid Robot ver.1), over broad ditches. two-dimensional gaits are chosen along with trajectory planning to calculate the thrust torque offered by the ducted fan for balancing the gravitational moment. The effectiveness and practicality are validated by Jet-HR1 stepping over a wide ditch with 370 mm, using almost 80% of its leg, both in simulation and experiment.