An ornithopter includes a main wing mounted on a fuselage, and a control system configured to control a flapping motion of the main wing. The main wing includes an inner spar, an outer spar, and a wrist portion disposed between the inner spar and the outer spar and which varies a bending angle, which is a relative angle between the inner spar and the outer spar, within a predetermined angle range. The control system includes an actuator which performs a raising motion and a lowering motion of the inner spar by moving the inner spar in an upward direction and in a downward direction, an angle sensor which measures the bending angle, and a control unit which controls the actuator to move the inner spar in response to the measured bending angle.