To stably and favorably supply a lubrication oil without increase in number of parts.
This planetary roller power transmission device is so constructed that a plurality of first rollers 23 and second roller 24 arranged at equal spaces in the circumferential direction between a sun roller 21 and an outer ring 22 concentrically disposed on the outer periphery side are arranged in multistage in the radial direction, and the sun roller 21 and the first rollers, and the second rollers 24 and the outer ring 22 are pressed to each other, and power is transmitted through an oil film formed between the respective frictional contact surfaces by a lubricant by shearing force of the oil film. In this device, the lubricant is lubricating grease having worked penetration at 25°C ranging from 350 to 500.
NOZAKI TAKASHI