Provided is a travel motion assist device capable of assisting a travel motion of a user without causing any discomfort, and has a high level of versatility. A travel motion assist device includes an assist drive unit configured to be worn on a prescribed joint of the user required for the travel motion of the user, and to be driven in a corresponding manner, a torso motion detection unit configured to be worn on a torso of the user, and to detect the displacement of a center of gravity C indicating the movement of the torso, and a control unit configured to control an operation of the assist drive unit, wherein the control unit estimates a phase of the travel motion of the user according to a detection result of the torso motion detection unit, and drives the assist drive unit at a prescribed phase.