To provide a helicopter which can be installed to the back side of a pilot, take off/land and fly in that state, and become more compact when not flying as compared with when flying.

The helicopter A1 comprises a machine body 1; a main rotor 2 provided with rotor blades to a rotor shaft so as to flap; a tail rotor 3 provided at a tip end of a tail 12 of the machine body 1; an engine 4 driving rotors 2, 3; a control stick 5 steering by adjusting a number of rotations of the main rotor 2, a tilting angle of a rotation surface, and a number of rotations of the tail rotor 3; and an installing belt 6 enabling the pilot to install the machine body 1 on a back side. An expanding/contracting tail 12 of the machine body 1 can be contracted.