A high-lift device of a flight vehicle includes: a flap main body provided at a trailing edge portion of a main wing of the flight vehicle so as to be extracted from and be retracted in the trailing edge portion and extending in a wing span direction of the main wing; and a vortex suppressing portion provided at a tip end portion of the flap main body in a wing span direction of the flap main body and configured to suppress a vortex rolling up from a lower surface of a tip end portion of the flap main body to an upper surface of the tip end portion.