To provide a technology for reducing a drag phenomenon.

A braking means 68 is provided with a first brake drum 79 formed at the outer periphery of a ring gear 66, first brake shoes 92, 92 provided on the inner side of the first brake drum 79 so as to come into contact and leave, second brake shoes 97, 97 provided integrally with the first brake shoes 92, 92 toward an output shaft 65, and a second brake drum 84 provided in a support body 64 coaxially with the output shaft 65 to prevent the drag phenomenon of the support body by abutting the second brake shoes 97, 97. When the ring gear performs idling and the power of an input shaft is not transmitted to the output shaft, the second brake drum on an output shaft side can be pressed by the second brake shoes to suppress the drag phenomenon completely. As a result, reliability in switching the transmission of power and the non-transmission of power in this planetary gear type power device can be improved.