To provide a traction drive requiring no special pressurizing mechanism, easily allowing large deformation, hardly allowing reduction of a pressure- contact load to slight abrasion, allowing easy inspection for confirming that the pressure-contact load is a desired value, and allowing easy configuration of a hollow structure.

This traction drive type driving device comprises a circumscribed shaft 2 provided at its center A, plural middle shafts 1 evenly disposed around the circumscribed shaft 2 and circumscribing the circumscribed shaft 2, and an inscribed cylinder 3 inscribed by the middle shafts 1. At least one of the middle shafts 1 offset from the center A is an input shaft. The circumscribed shaft 2 is a ring-like hollow cylinder. The circumscribed shaft 2 is held by the middle shafts 1 without a special support bearing, that is, the circumscribed shaft 2 is a floating ring.