A strain wave gearing device has a grease temperature control mechanism for controlling the grease temperature of a portion of grease, of the grease filled inside an externally toothed gear of the strain wave gearing device, the portion of the grease being disposed on the outer peripheral side portion of a wave generator. The grease temperature control mechanism has a circular heater facing the outer peripheral side portion of the wave generator over the entire circumference from a direction of a device central axis line. By controlling the grease temperature of a specified portion inside the externally toothed gear, it is possible to reliably start the strain wave gearing device even in an extremely low temperature environment where the grease solidifies.