Abstract: There is provided a compact and highly durable variable-speed traction drive transmission device. A traction drive transmission device which uses the traction of rolling bodies K arranged between an input shaft Si and an output shaft So to change the number of revolutions of the input shaft Si into a desired transmission ratio and output from the output shaft So, has a rotation axis of the rolling bodies K arranged at an incline so that it is not orthogonal to the axis of the input shaft Si and the output shaft So, and there is provided: a load regulation cam 50 which automatically changes a preload applied to the rolling bodies K corresponding to a torque of the input shaft Si; and a differential type transmission ratio variation mechanism using a worm gear 55, which is connected to a retainer 40 serving as a traction input-output member of the rolling bodies K, and performs number of revolutions control of the retainer 40 to change the transmission ratio.