A device for assisting a users motion in an appropriate rhythm by bringing a users motion rhythm close to its target rhythm while harmonizing the motion rhythms of different parts of the users body and a rhythm for assisting the users motion is provided. The inventive walking assist device generates a first oscillator which attains mutual entrainment with a first motion oscillator in such a way as to reflect a natural angular velocity. A new natural angular velocity is set based on a phase difference between the first motion oscillator and the first oscillator. Further, a second oscillator which oscillates in a rhythm reflecting the natural angular velocity is generated based on a second motion oscillator. An assist oscillator is then generated based on the second oscillator, and a variable force responsive to the assist oscillator is applied to the users body.
