An unmanned aircraft system includes a manned aircraft and an unmanned aircraft. The manned aircraft includes a manned aircraft main wing, a manned aircraft fuselage, a manned aircraft landing system, and a manned aircraft joining mechanism provided at a bottom portion of the manned aircraft fuselage. The unmanned aircraft includes an unmanned aircraft main wing, an unmanned aircraft fuselage, an unmanned aircraft landing system, and an unmanned aircraft joining mechanism provided at a roof portion of the unmanned aircraft fuselage. The manned aircraft joining mechanism and the unmanned aircraft joining mechanism are detachably joined. The unmanned aircraft system can take off or land in a state that the unmanned aircraft and the manned aircraft are joined.