PURPOSE: To absorb an impact when a space airship touches the airstrip and to perform its landing easily and safely, by installing a flexible bag inflatably sealed up in the underside of a machine body in this space airship, and inflating this bag when the airship is landed.

CONSTITUTION: In a machine body 5 of a space airship whose flat form is a round shape, there are provided three balloonlike bags 2, by way of example, in and around the under surface at regular intervals. On the other hand, a gas accumulator 1 is installed in an inner part of the machine body 5, and it is connected to each bag 2 by a pipeline 7 with a valve 6. In an intermediate part of these adjacent bags 2 on the underside of the machine body 5, there are provided with three load supporting points 3 likewise. When the space airship is landed on the moon and so on, the valve 6 is opened and gas in the gas accumulator 1 is injected into each bag 2. With this constitution, each bag 2 is inflated whereby an impact at time of grounding of the machine body 5 is absorbed. Afterward, each of these bags is deflated, supporting the machine body 5 with the load supporting points 3.