PURPOSE: To effectively take out energy from wind or so for accumulative utilization thereof by lifting weights up and down by means of an energy generating source such as a windmill via differentials so as to properly drive a generator or the like.

CONSTITUTION: A windmill 1, for example, among a variety of energy generating sources is disposed at the upper part of a tower etc. and a rotary shaft 2 thereof is connected to a plurality of differentials 3, to which weights 4, a change-over rod 6 and pulleys 9 are mounted. By rotation of said windmill 1, the weights 4 are alternately lifted up and down by means of the change-over rod 6 via the revolving shaft 2 and the differentials 3. By repeatedly effecting the up and down motion, a generator 5 which is connected to one end of the pulley 9 is driven. The energy of wind or so is thus effectively taken out for accumulative use.