PURPOSE: To effectively take out wind-power energy which is constantly strong in the upper air of the sky in such a way that a windmill power generator is installed on the outside of a dirigible which holds a gas that is ligher than air and has its main planes to yield dynamic lift, and power is transmitted through a cable which moors the hull to the ground toward the ground.

CONSTITUTION: A gas which is lighter than air is held into the hull 1. The structure of the hull 1 is desirable to be a hard dirigible to withstand wind pressure of strong jet air current in the upper air of the sky, and its outward form is quasispindle shape whose sectional form is a circle. Fitting frames 3, 4 of a ring-shaped windmill power generator 5 are installed near the leading edge part and the trailing edge part of the hull 1. Besides, longitudinal stabilizing fixed horizontal tail planes 6, wind vane stabilizing vertical tail planes 7 and main planes 2 are arranged on the hull 1. In addition, the hull 1 is moored to the ground through a cable 8 by way of which power can be transmitted toward the ground.