A wearable device is disclosed. A wearable device according to an embodiment relates to a mechanism, including: a wearing unit configured to be mounted on any one of a human, an animal, and a mechanical device; a housing configured to be coupled to the wearing unit and to accommodate a tool having a predetermined function; and a power transmission unit configured such that one end thereof is coupled to a part of the wearing unit and the other end thereof comes into contact with the tool, thereby moving in conjunction with movement of the human, animal or mechanical device and transmitting force to the tool; wherein when a part of the human, animal, or mechanical device moves, the tool receives force from the power transmission unit and projects out of the housing, and to the utilization of the mechanism.