To change the research attitude following a space shuttle of a rocket dumping manner, and to enable coming of an amphibious space plane age unique to Japan.

The amphibious space plane has a structure where a rocket fuel tank and a plane fuselage are unified to enlarge the seat storable area, the strength of the whole plane is increased by a distributed load using the whole lower surface of the fuselage as wetting bottom surface to remarkably increase loading capacity of staff and cargo, and rocket injection ports adjustable in injection direction are mounted to both ends of the main wing and both ends of the horizontal tail of the plane. The amphibious space plane having an extremely large speed variation range from supersonic space flight to semi-vertical taking-off from water and vertical splashdown or vertical landing is developed, about 1,000-2,000 passengers are carried, space inertial flight allows the plane to cross Pacific Ocean in about 1 hour.