An assist device includes a body wearing unit configured to be worn on a body of a user including a region around an assist target body part of the user and an actuator unit configured to be attached to the body wearing unit and to the assist target body part so as to assist a motion of the assist target body part. The body wearing unit includes a main frame having a pivot shaft portion, and a sub-frame connected to the pivot shaft portion and configured to pivot around an axis of the pivot shaft portion. The sub-frame is pivotable so as to fit a body size of the user.
