A flight control method and device for correcting a reference trajectory based on a distance from a current position to a target position in a spacecraft in flight. A CPU included in the spacecraft generates a reference trajectory which is a trajectory for allowing the spacecraft in flight to arrive at the target position on a celestial body with the atmosphere, and which is identified based on velocity or energy of the spacecraft and on drag acceleration of the spacecraft. The CPU calculates a ratio between the range that is a distance from the current position based on the reference trajectory to the target position, and the real range that is a real distance from a current position to the target position, and corrects the reference trajectory by calculating the drag acceleration in the reference trajectory using the calculated ratio.