Abstract: A brake device includes a brake mechanism including a shaft received in a brake chamber capable of being filled with a liquid, the brake mechanism being configured to switch between a braking applied state, in which the brake mechanism restricts a rotational motion of the shaft by generating a braking force, and a braking released state, in which the brake mechanism permits the rotational motion of the shaft by not generating the braking force. In the brake device, the brake chamber is filled with the liquid in the braking applied state, and the brake chamber is evacuated of the liquid in the braking released state.