PROBLEM TO BE SOLVED: To provide an assist device capable of reducing a burden on a user when it is mounted.SOLUTION: An assist device for assisting a movement of a joint between a first part and a second part of a human body includes a first member mounted on the first part, a second member mounted on the second part, and a speed reducer 132 interposed between the first member and the second member. The speed reducer 132 includes an external tooth gear 35 and a housing 33 connected to the first member, and an internal tooth gear 34 connected to the second member. The assist device further includes a connection mechanism 140 for connecting the second member and the internal tooth gear 34 in a rotation direction, and an operation member provided so as to be operated from the outside of the speed reducer 132 that can perform an operation to release the connection of the connection mechanism 140.SELECTED DRAWING: Figure 4
