A brake device includes: an outer race having a cylindrical inner peripheral surface; at least two brake cams arranged inside the outer race in a circumferential direction, each brake cam having brake surfaces located at both ends in the circumferential direction of a side of the brake cam facing the outer race, each brake surface being contactable with the inner peripheral surface of the outer race; and an output-side rotary member arranged at radially inner sides of the respective brake cams, the output-side rotary member including contact portions contactable with surfaces of the brake cams facing the radially inner sides. Contact points at which the respective contact portions and the respective brake cams are contactable are on an axis-of-rotation side of a both-end reference plane (plane connecting outer ends of the respective brake surfaces located at the both ends of to corresponding brake cam), or on the both-end reference plane.