When performing actuator control using weight on the bottom of the foot as a trigger, the foot of the user must appropriately touch the ground in order for the weight to be sensed. Therefore, the activation condition for starting the actuator control is limited and, for example, a rehabilitation patient who has one injured leg has difficulty training their step movement using this step assist device. Provided is a step assist device including a providing section that provides an assist force to a step movement of a user； a detecting section that detects a hip joint angle, which is an angle of aperture of a hip joint of the user； and a control section that begins controlling the providing section when the hip joint angle exceeds a predetermined threshold value, according to an assistance plan set in advance for the step movement of a single step of the user.
