To provide a power buffer device capable of smoothly braking wheels in braking operation of rear wheels and comfortable operation when turning.

An intermediate slider 45 is placed movably in the axial direction between a drive-side cam 39 as a drive-side rotary member and a driven- side sleeve 42 as a driven-side rotary member, and a cam mechanism 54 and dog clutch mechanism 55 are respectively placed between the intermediate slider 45 and the drive-side cam 38, and between the intermediate slider 45 and the driven-side sleeve 42. A friction cone 46 and a coil spring 47 axially biasing the friction cone 46 provide the cam mechanism with cam resistance, the coil spring 47 biases the intermediate slider 45 to get off from the driven-side sleeve 52, and thereby the dog clutch mechanism 55 is maintained in the disconnected state.