To provide a friction-type power transmission capable of easily assembled at low cost.

In a planetary ball-type transmission 1, a plurality of planetary balls 32 are rotatably held by a carrier 34, rotated while being brought into external-contact with a sun roller 31, pinched between a pair of annular outer rings 33, and to be brought into internal-contact with a pair of outer rings 33. A pair of outer rings 33 are energized by a pair of elastic members 35 so as to be approached to each other. The elastic members 35 are interposed between a easing 30 and the outer rings 33 to enable axial relative movement between the outer rings 33 and the casing 30 and to regulate the relative rotation. When the sun roller 31 is deviated in the axial direction, the planetary balls 32 and the outer rings 33 can be axially displaced by following the sun roller 31, and power transmission can be naturally performed. Therefore, assembling costs and costs of parts can be reduced.