To provide 'a gravity converting prime mover' constituted by generating power (energy) without using external fuel generating pollution such as fossil fuel in the generation of power.

A center shaft 1 and a pulley 2 with applied weight are connected by a telescopic fork 3 and an annular track 5 with an incorporated guide pulley 4 is equipped on a frame 9. By a rotating operation of a screw shaft 7 provided with a spiral screw, the annular track 5 is slid on a horizontal line and elongation and contraction of the telescopic fork 3 is accelerated. By elongation and contraction, power of the pulley 2 is converted and the pulley 2 is rotated.