To lower a flying body slowly and safely even if a fire of a burner is extinguished and an air-sac is broken by attaching the air-sac of a balloon and an airship and a parachute for preventing crash on the circumference of the air-sac in peripheral shape or in peripheral shape which is knotched in a part.

A gondola 3 in which an occupant rides and a burner 4 which sends heated air to an air-sac 1 are hung in a lower part of the air-sac 1 of for example, heat balloon. A skirtlike parachute 2 is provided in a slightly lower part of the air-sac 1, and its air resistance is supported by a support sac 5. Furthermore, the parachute 2 is provided with two vent holes 7, and a wind exhaust adjusting valve which can be opened and closed by an operation rope 6 is provided in the holes 7. In a condition in which two vent holes 7 are opened, the heat balloon descends in the direction of center of an angle formed by two vent holes 7. When vent holes 7 on the right and left sides are closed, the neat balloon descends in the right and left directions, respectively. When both vent holes 7 are closed, its direction of descent cannot be controlled, but its speed of descent can be reduced greatly.