To provide a vertical tail of an aircraft capable of improving simple easiness when stored and stability against side wind, etc., reducing a cost and achieving high safety.

This vertical tail 10 is arranged together with a horizontal tail 5 in a rear part of the airframe to constitute the tail. The vertical tail 10 comprises the main vertical tail 11 fixed and arranged at a prescribed portion of the airframe and an auxiliary vertical tail 12 variably constituted to be stored, deployed and mounted. The auxiliary vertical tail 12 is deployed and mounted according to airspeed to change the whole area of the vertical tail 10 constituted of the main vertical tail 11 and the auxiliary vertical tail 12.